Chevron Offshore (Thailand) Ltd
0 PH Issued for Use 8/2001
A MLJ Issue for Review 6/2000
TABLE OF CONTENTS
1.0 INTRODUCTION
1.1 Scope
1.2 Exclusions
1.3 Responsibilities
1.4 Conflicts and Exceptions
2.0 MANDATORY CODES AND STANDARDS 3.0 GENERAL REQUIREMENTS
4.0 WELDING
4.1 General
4.2 Welding Processes
4.3 Welding Procedure Qualification
4.4 Welder and Welding Operator Qualification
4.5 Production Welding
5.0 FABRICATION, ASSEMBLY AND ERECTION
5.1 General Piping
5.2 Pipe Supports
6.0 POST WELD HEAT TREATMENT
6.1 General
6.2 Exothermic Heat Treatment
7.0 QUALITY ASSURANCE AND QUALITY CONTROL
7.1 General
7.2 Radiography
8.0 FLUSHING AND HYDROSTATIC TESTING
8.1 General
8.2 Preparation for Testing
8.3 Hydrostatic Leak Testing
8.4 Post-Test Requirements
9.0 PNUEMATIC TESTING
9.1 General
9.2 Pneumatic Leak Testing
10.0 CLEANING, DESCALING AND PASSIVATING STEEL PIPING
10.1 General
10.2 Acid Descaling (Pickling) and Passivation
10.3 Abrasive Blasting
10.4 Hot Oil Flushing
11.0 PROTECTIVE COATINGS
12.0 IDENTIFICATION AND MARKINGS
13.0 PREPARATION FOR SHIPMENT AND STORAGE 14.0 DOCUMENTATION REQUIREMENTS
APPENDICES
I Mandatory Codes and Standards
II Additional Requirements for Duplex Stainless Steel Piping
III Additional Requirements for Fiberglass Reinforced Plastic (FRP) Piping
IV Additional Requirements for Chlorinated Poly Vinyl Chloride (CPVC) Piping
1.0 INTRODUCTION 1.1 Scope
1.1.1 This specification, in conjunction with the other Technical Requirements, defines
the minimum acceptable requirements for the fabrication, assembly, welding, erection, installation, inspection, testing, cleaning and documentation of carbon and austenitic stainless steel piping systems used in upstream oil and gas production facilities. This specification governs piping systems provided in accordance with API Recommended Practice 14E "Design and Installation of Offshore Production Piping Systems" and ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping."
1.1.2 Piping systems constructed of duplex stainless steel materials shall meet the
additional requirements specified in Appendix II "Additional Requirements for Duplex Stainless Steel Piping."
1.1.3 Piping systems constructed of Fiberglass Reinforced Plastic (FRP) materials
shall meet the additional requirements specified in Appendix III "Additional Requirements for Fiberglass Reinforced Plastic (FRP) Piping."
1.1.4 Piping systems constructed of Chlorinated Poly Vinyl Chloride (CPVC) materials
shall meet the additional requirements specified in Appendix IV "Additional Requirements for Chlorinated Poly Vinyl Chloride (CPVC) Piping."
1.1.5 Piping systems constructed API 5L Grade X-60 materials shall meet the
additional requirements specified in Appendix V "Additional Requirements for API 5L Grade X-60 Carbon Steel Piping."
1.1.6 This specification shall also apply to the fabrication and attachment of pipe supports.
1.2 Exclusions
This specification does not apply to process design, line sizing, or equipment layout; nor does it apply to piping material and component selection, or to piping design and layout. Specific exclusions include all small bore instrument tubing, sub-sea pipelines, risers and J-tubes.
1.3 Responsibilities
CONTRACTOR shall be solely responsible for providing complete and operable piping systems in full accordance with all applicable Industry Codes and Standards, Government Regulations and COMPANY Technical Requirements.
1.4 Conflicts and Exceptions
1.4.1 All conflicts between this specification, the other Technical Requirements, and
the applicable codes and standards shall be submitted in writing to COMPANY for resolution.
1.4.2 Any and all exceptions to the Technical Requirements shall be submitted in
2.0 MANDATORY CODES AND STANDARDS
2.1 The primary codes governing piping systems provided under this specification
shall be API Recommended Practice 14E "Design and Installation of Offshore Production Piping Systems" and ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping."
2.2 The most recent issue of the codes and standards listed in Appendix I
"Mandatory Codes and Standards" shall be considered as a part of this specification.
2.3 Special design allowances outlined in any of the codes and standards may not
be used without written approval of COMPANY.
2.4 COMPANY "Safety in Designs" Manual (GO-590) shall be considered as part of
this specification. CONTRACTOR shall refer to COMPANY "Safety in Designs" Manual regarding all safety concerns related to piping system design, layout, fabrication and assembly, such as valve accessibility guidelines, overhead clearance requirements and valve handwheel/stem position limitations.
3.0 GENERAL REQUIREMENTS
3.1 The fabrication, assembly, welding, erection, installation, inspection, testing,
cleaning and documentation of piping systems shall be in full accordance with API RP 14E "Design and Installation of Offshore Production Piping Systems," ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping" and COMPANY Technical Requirements. All addenda issued through the date of the Purchase Order, Contract or Agreement, as applicable, shall apply in full.
3.2 The fabrication, installation, inspection and testing of Polypropylene Lined (PPL)
carbon steel piping systems shall be in accordance with ASTM F492 "Propylene and Polypropylene (PP) Plastic-Lined Ferrous Metal Pipe and Fittings," the manufacturer's requirements and recommendations, and the Technical Requirements. Welding and field branch connections shall not be permitted on pre-fabricated, lined spool pieces.
3.3 The fabrication, installation, inspection and testing of Fiberglass Reinforced
Plastic (FRP) piping systems shall be in accordance with the manufacturer’s requirements and recommendations, and the Technical Requirements.
CONTRACTOR shall note that the Technical Requirements do not include complete, detailed piping fabrication, inspection or testing requirements specific to the needs of FRP piping systems. CONTRACTOR shall be responsible for developing piping fabrication, inspection or testing requirements to the mutual satisfaction of COMPANY and the FRP piping manufacturer.
3.4 The fabrication, installation, inspection and testing of Chlorinated Poly Vinyl
Chloride (CPVC) piping systems shall be in accordance with ASTM D2846 "Specification for Chlorinated Poly Vinyl Chloride (CPVC) Plastic Hot and Cold Water Distribution Systems," the manufacturer’s requirements and recommendations, and the Technical Requirements.
3.5 The selection of pipe, piping components and valving shall be in full accordance with the Technical Requirements, including General Specification 3.00 "Piping Service Classifications and Material Requirements," and in particular the appropriate Material Class Data Sheet for the intended service. Substitution of alternate materials or components shall require prior written approval by COMPANY.
3.6 Pipe support materials shall be provided in accordance with the Technical
Requirements. As a minimum, pipe supports shall be fabricated from carbon steel that meets the requirements of ASTM A36 or ASTM A-53, A-106-B or API 5L, Grade B pipe, unless specified otherwise.
3.7 References in this specification to ANSI Class 150, 300, 600, 900, 1500 and
2500 flange ratings refer to ANSI B16.5 "Pipe Flanges and Flanged Fittings." References to API 3000, 5000 and 10,000 pound flange ratings refer to API 6A "Specification for Wellhead Equipment."
3.8 All sour service hydrocarbon piping systems shall be in accordance with NACE
MR-01-75 "Sulfide Stress Cracking Resistant Metallic Material for Oil Field Equipment."
3.9 CONTRACTOR shall not proceed with material purchasing or fabrication without
approval of COMPANY.
3.10 As a minimum, all workmanship shall be equal to standard commercial practice in
modern fabrication shops. All work shall be performed by workmen skill in their trades. All materials and equipment shall be new and of high quality manufacture.
4.0 WELDING 4.1 General
4.1.1 All welding shall be in strict accordance with ANSI B31.3 "Chemical Plant and
Petroleum Refinery Piping," the ASME "Boiler and Pressure Vessel Code" - Section IX "Welding and Brazing Qualifications" and the COMPANY Technical Requirements. The welding processes as discussed in this section shall be acceptable for CONTRACTOR’s use in the fabrication of piping and pipe supports unless otherwise noted in the Technical Requirements.
4.1.2 All welding procedures shall be in writing and shall be qualified in accordance
with the ASME "Boiler and Pressure Vessel Code" - Section IX "Welding and Brazing Qualifications" as modified by ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping." All Weld Procedure Specifications (WPS) and Procedure Qualification Records (PQR) shall be submitted to COMPANY for approval prior to any welding.
4.1.3 Only welders qualified in accordance with the ASME "Boiler and Pressure
Vessel Code" shall be utilized for fabrication. Welders shall have their qualification certificates available for COMPANY review during all stages of fabrication. If requested by COMPANY, CONTRACTOR shall submit a list of qualified welders and the procedures for which they have been qualified. COMPANY may, at it’s option, require new qualification tests for any welder working on piping fabrication. Should the welder fail the new qualification tests,
then CONTRACTOR shall bear all costs for the tests and the welder shall be removed from the work. COMPANY will reimburse CONTRACTOR reasonable costs of new qualification tests passed by the welder in question.
4.1.4 All welding processes shall be identified by number. Identification numbers shall
be referenced on all fabrication drawings. CONTRACTOR shall submit fabrication drawings or weld maps that identify the proposed welding process for each weld, or types of weld configurations, prior to the start of welding.
4.1.5 COMPANY shall reject any weld that has not been made properly. Defects in
welds or fabrication, including fit-up, shall not be permitted which in the opinion of COMPANY are detrimental to the strength of the weld. All repair procedures shall be submitted to COMPANY for approval prior to start of repair work. The cost of preparing repair procedures and repairing defective welds shall to the CONTRACTOR’s account, not the COMPANY.
4.1.6 Any weld tampered with or caulked in any way shall be condemned whether or
not it is sound. "Doctoring" the surface of defective welds with a torch shall not be permitted under any circumstances.
4.1.7 All welding equipment shall be in good condition and subject to inspection by
COMPANY. Any equipment found in need of repair shall be removed from the fabrication work until said repair is completed.
4.2 Welding Processes
4.2.1 General
4.2.1.1 Acceptable weld processes for welding of piping and supports shall include the
following:
•Flux Core-Arc Welding (FCAW)
•Gas Metal-Arc Welding (GMAW)
•Gas Tungsten-Arc Welding (GTAW)
•Shielded Metal-Arc Welding (SMAW)
•Submerged-Arc Welding (SAW).
4.2.1.2 Oxyacetylene welding shall not be permitted.
4.2.1.3 All semi-automatic or fully-automatic welds shall be made utilizing a multi-pass
technique.
4.2.2 Flux Core-Arc Welding (FCAW)
a. Wind velocities shall not exceed 5 mph in the weld area.
b. Gas shielded electrodes shall always be utilized, and the electrode diameter shall not exceed 1/8".
d. Self-shielded FCAW shall not be permitted for process piping, but may be used for pipe support fabrication.
e. Low hydrogen consumables shall be certified by the electrode CONTRACTOR, or tested by CONTRACTOR to result in less than 10 ml of diffusible hydrogen per 100 gm of deposited weld metal. Diffusible hydrogen content shall be measured by the mercury displacement or gas chromatograph method per AWS A4.3. CONTRACTOR shall provide written evidence of compliance with this requirement. The specification sheet for the proposed brand of filler metal from the CONTRACTOR shall be acceptable as written evidence.
4.2.3 Gas Metal-Arc Welding (GMAW)
a. Wind velocities shall not exceed 5 mph in the weld area.
b. Short-arc GMAW shall be used only for root pass butt welding on piping. c. Short-arc GMAW shall not be used on weld-o-lets, reinforced nozzles and
branch welds, couplings, slip-on flanges, socket welds or other pipe appurtenances.
4.2.4 Gas Tungsten-Arc Welding (GTAW)
a. Wind velocities shall not exceed 5 mph in the weld area.
b. An internal gas purge shall be provided for the root pass and the second layer of autogenous and stainless steel welds.
4.2.5 Shielded Metal-Arc Welding (SMAW)
a. Wind velocities shall not exceed 10 mph in the weld area. b. Low hydrogen electrodes shall be required.
c. If SMAW low hydrogen electrodes are unsuitable for producing acceptable radiograph quality, then GTAW, GMAW, or cellulosic SMAW electrodes shall be used on the root pass on single-sided butt welds.
d. Cellulosic SMAW electrodes shall not be permitted for welds on API flanges.
4.2.6 Submerged-Arc Welding (SAW)
a. Wind velocities shall not exceed 10 mph in the weld area.
b. All welding shall be multipass, with semi- or fully-automatic equipment. c. Weld passes shall not be greater than 3/8" thick.
d. Addition of alloy agents through the flux shall not be acceptable.
4.2.7 Filler Metals, Electrodes, Wire and Flux
4.2.7.1 Electrodes, wires and fluxes shall be selected to produce welds with mechanical
properties not less than those of the base metal. Filler metal for welding similar materials shall be of the same nominal analysis as the base metal, except E-347 electrodes shall be used for SMAW welding of Type 321 material. When
welding two steels of unequal strengths, the welding wire or electrode shall be matched to the higher strength material.
4.2.7.2 The weld filler metal in low-temperature piping service shall meet the same impact test requirements as the base metal.
4.2.7.3 Tensile strength of deposited weld metal shall be limited to 100 ksi maximum
and shall be verified by a hardness test of the weld material in the procedure qualification. Weld metal hardness shall not exceed 200 Brinell.
4.2.7.4 Carbon steel electrodes for welding API 5L, Grades B and X-42 pipe shall conform to the following ASME specifications:
•SMAW ASME SFA-5.1
•GTAW/GMAW ASME SFA-5.18
•SAW ASME SFA-5.17
•FCAW ASME SFA-5.20 Classes:
E60T-1, E60T-5, E61T-1, E61T-5 E70T-1, E70T-5, E71T-1, E71T-5
4.2.7.5 Stainless steel electrodes shall be low carbon "L" grade, and shall conform to
the following ASME specifications:
•SMAW ASME SFA-5.4
•GTAW/GMAW ASME SFA-5.9
•FCAW-g ASME SFA-5.22
4.2.7.6 Filler metals for joining carbon steels to stainless steels shall be E309L, except
in services over 600°F where Inco 182 shall be used. Low carbon grades of austenitic stainless steel shall be joined with low carbon weld metal of corresponding composition.
4.2.7.7 The following SMAW SFA-5.1 electrode classifications shall not be acceptable
for pressure containing welds:
•E6012 •E6013 •E6020 •E7014 •E7020 •E7024.
4.3 Welding Procedure Qualification
4.3.1 All weld procedures shall have been qualified no more than 6 years prior to the
date of the Contract, Agreement or Purchase Order as applicable. Provided that the Welding Procedure Specifications (WPS) and Procedure Qualification Records (PQR) are in full accordance with the Technical Requirements, qualification of new procedures will be waived by COMPANY.
4.3.2 If new weld procedures or new procedure qualifications are required, CONTRACTOR shall bear all costs. All procedure qualifications shall be performed by an independent testing laboratory suitable to COMPANY. COMPANY shall, at its option, witness the procedure qualifications.
4.3.3 Procedure qualifications shall include the composition and flowrate of inert gas
backing when used.
4.3.4 For low-temperature services, i.e. 34°F and below, procedure qualifications for
ferritic materials shall include impact tests of both the weld metal and the heat affected zones, even if impact tests are not required on the base material. SMAW welds shall only require testing if impact test are required for the base material.
4.3.5 SAW procedure qualification test records shall show the name of the
manufacturer and the trade name of the wire and flux used to qualify the procedure.
4.3.6 The welding procedure tests shall demonstrate that all details are satisfactory
for obtaining full penetration welds for the following types of joints:
•Double-welded longitudinal and circumferential butt joints
•Single-welded longitudinal and circumferential butt joints made without a backing ring.
4.3.7 Hardness testing shall be performed as part of the weld procedure qualification
for all sour service carbon steel piping. Two hardness traverses, including weld metal, heat affected zone (HAZ), and base metal, shall be made on a polished and etched cross-section of the weld at 1 to 2 mm below the cap pass, and 1 to 2 mm above the root pass. Readings shall be taken every 2 mm in the weld metal and base metal, and every 1 mm in the HAZ, with a minimum of 3 readings in each zone. Maximum hardness shall not exceed Vickers 250 using a load not exceeding 22 pounds (10 kg).
4.4 Welder and Welding Operator Qualification
4.4.1 Welders and welding operators shall have been qualified within the 6 months
prior to beginning of fabrication in accordance with the ASME "Boiler and Pressure Vessel Code" - Section IX "Welding and Brazing Qualifications."
4.4.2 All welder qualifications and certificates with picture identification shall be submitted to COMPANY for approval prior to any fabrication. If existing welder qualifications are judged inadequate by COMPANY and welders must be requalified, welder re-qualification shall be performed at CONTRACTOR’s expense.
4.4.3 COMPANY reserves the right to witness all welder re-qualification tests.
CONTRACTOR shall notify COMPANY a minimum of two weeks prior to the tests to allow COMPANY to witness the tests.
4.4.4 Radiographic examination of a qualification test plate (or pipe) in lieu of mechanical testing shall not be accepted by COMPANY.
4.4.5 Welders shall have their qualification certificates with picture identification at the work site during all fabrication.
4.5 Production Welding
4.5.1 Joint Preparation and Fit-up
4.5.1.1 Surfaces to be welded shall be clean and free from all galvanizing, paint, oil,
dirt, scale, oxides or other materials detrimental to welding.
4.5.1.2 Weld bevels shall be suitable for the welding process selected and shall conform to the bevel in the weld procedure specification. Bevel contour shall permit complete fusion throughout the joint.
4.5.1.3 Weld bevels shall be made by machining, grinding or thermal cutting, and shall
be reasonably smooth and true. Materials that require preheat for welding shall be preheated in the same manner for thermal cutting or gouging.
4.5.1.4 Prior to welding, all laminations, split ends and other defects shall be called to
the attention of COMPANY and shall be cropped, repaired or removed as directed by COMPANY.
4.5.1.5 The use of backing rings, backup strips, strong backs or welded lugs shall not
be permitted.
4.5.1.6 Line-up clamps shall be used when necessary to ensure that fit-up is within
design tolerances. Line-up clamps shall not be removed until a continuous stringer bead equal to one quarter of the circumference of the pipe has been completed on both sides of the pipe.
4.5.1.7 Consumable inserts may be used only with written authorization from
COMPANY. Approval for use of consumable inserts shall be obtained prior to the start of fabrication and included in the Procedure Qualifications as required by ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping."
4.5.1.8 If the wall thickness difference in a butt-weld joint is greater than 1/16", a transition in accordance with API 14E "Design and Installation of Offshore Production Piping Systems" - Appendix B "Acceptable Butt Welded Joint Design for Unequal Wall Thicknesses" shall be required. The maximum offset shall be 1/16", not 3/32" as allowed by API 14E.
4.5.1.9 If component ends must be trimmed to correct internal misalignment in
accordance with API 14E "Design and Installation of Offshore Production Piping Systems," the trimming shall not reduce the finished wall thickness below the required wall thickness (tm) for the pipe or fitting. The required wall thickness (tm)
shall be defined as the design wall thickness including all mechanical, corrosion and erosion allowances.
4.5.1.10 If the required taper in accordance with API 14E "Design and Installation of Offshore Production Piping Systems" would result in a trimmed wall thickness
less than the required wall thickness (tm), then CONTRACTOR shall fabricate a
transition spool. This spool shall be fabricated from material equal in grade to the highest grade material to be welded, and shall have a wall thickness equal to the thicker pipe or fitting to be welded. The transition spool length shall be at least one and one half times the nominal pipe diameter, but no less than 12" in
length. The transition spool shall be internally tapered at one end to match the thickness of the thinner walled pipe or fitting, and beveled for welding. The taper angle shall be approximately 4:1, but not less than 14 degrees. CONTRACTOR shall stencil all transition spools with the pipe size, grade and wall thickness'.
4.5.2 Preheat
4.5.2.1 All welded joints shall be preheated in accordance with the approved weld procedures. The minimum preheat temperature for thermal cutting, tacking and welding shall be in accordance with ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping." Preheat shall be maintained during all multi-pass welding.
4.5.2.2 Additionally, preheating to 100°F shall be required if the base metal is damp, if
the surface temperature is less than 40°F or if the relative humidity is above
50%.
4.5.2.3 All API flanges shall be preheated to minimum 400°F before welding. Preheat
shall be maintained throughout the welding process.
4.5.3 Welding
4.5.3.1 COMPANY shall reject any weld that has not been properly made per the
Technical Requirements. All welds shall be made in such a manner as to reduce residual stresses.
4.5.3.2 Welding shall not be permitted at ambient temperatures less 40°F when either
the wind velocity exceeds 10 mph or the relative humidity exceeds 50%. Welding shall not be permitted in inclement weather unless both the welder and the work are well protected from the elements.
4.5.3.3 Electrodes, filler wires and fluxes shall be kept clean, dry and properly stored
according to the manufacturer's recommendations. Electrodes, filler wire or fluxes that are damp, greasy or oxidized shall not be used. During welding, care shall be taken to avoid contamination of fluxes.
4.5.3.4 Low hydrogen electrodes shall be protected from moisture and used within 2
hours of breaking the seal on their original (hermetically sealed) containers. If the container has been open for more than 2 hours, but less than 8 hours, the electrodes shall be placed in a heating box and held at 225°F for 8 hours minimum, and then used within 2 hours of removal from the hot box. Electrodes exposed longer than 8 hours shall be reconditioned by heating in an oven at
650 to 750°F for 1 hour minimum.
4.5.3.5 Weld beads shall be contoured to permit complete fusion at the sides of the
bevel and to minimize slag inclusions. Flux and slag shall be completely removed from weld beads, and from the surface of completed welds and adjoining base material. The flux shall be removed in a manner that will not contaminate or overheat the weld or adjoining base metal.
4.5.3.6 All welds shall be thoroughly cleaned after each pass by power wire brushing to
remove all slag, scale, splatter, coatings and dirt.
4.5.3.8 Welds on branches or reinforcing pads shall merge smoothly with the surface of the pipe. Sharp corners on reinforcing pads shall be removed.
4.5.3.9 Welding shall not be permitted on valves without prior written approval from
COMPANY.
4.5.3.10 Seal welding of threaded joints shall cover all exposed threads and blend smoothly into the pipe. Seal welds on threaded joints shall be made as small as possible using low penetration electrodes. Seal welds shall be tapered gradually.
4.5.3.11 Welds containing cracks, regardless of size or location, shall not be acceptable.
Cracks, notches, undercutting or any other evidence of poor workmanship shall be cause for rejection.
4.5.3.12 At the completion of all fabrication work, all excess weld metal, splatter, and
other foreign material shall be removed. Welds shall be wire brush cleaned to remove slag and weld spatter. On stainless steel piping, wire brushing shall be done only with stainless steel brushes which have not previously been used on ferritic materials. Edges shall be smoothed or rendered flush with the parent surface unless otherwise approved by COMPANY.
4.5.3.13 Stainless steel piping shall be kept free of surface contamination by iron or other foreign material. Excessive surface contamination and/or oxidation (heat tint) of welds shall be removed using an acid pickling solution or paste, or by blasting with iron-free grit.
4.5.4 Weld Repairs
4.5.4.1 Defective welds shall be plainly marked, cut out and repaired or replaced by
CONTRACTOR in accordance with the procedures specified in the ASME "Boiler and Pressure Vessel Code" - Section IX "Welding and Brazing Qualifications." CONTRACTOR shall advise COMPANY in writing of all required repairs prior to the start of repair work.
4.5.4.2 All costs associated with repairing defective welds shall be borne by
CONTRACTOR.
4.5.4.3 All unacceptable defects in the root or fill passes shall be entirely removed by
grinding or oxygen gouging to clean, sound metal. All slag and scale shall be removed by power brushing. Preheating of an area with a defect shall be in accordance with the original preheat requirements for the materials and type of weld.
4.5.4.4 External undercut shall be repaired by grinding off the weld cap in the undercut
location and recapping.
4.5.4.5 Arc burn defects shall be ground smooth provided that the depth of the defect
does not exceed 8% of the nominal wall thickness. Arc burn defects with a depth greater than 8% but less than 33-1/2% of the nominal wall thickness may be repaired by welding. The defect shall be thoroughly removed by grinding, then the cavity welded and ground smooth. The weld shall be preheated in accordance with the original preheat requirements for the materials and type of weld. Arc burns in excess of 33-1/2% of the nominal wall thickness shall be
removed by replacing a section of the pipe or fitting in accordance with the following paragraph.
4.5.4.6 Welds may be cut out and repaired in one location a maximum of two times. If
the second repair is found to be defective, then a section of the pipe no less than 2'-0" in length (including fittings) shall be removed and replaced. All new welds in the repaired section shall be radiographed and heat treated (if originally required) at CONTRACTOR’s expense.
4.5.4.7 After completion of the weld repair, the entire circumference shall be
radiographed using the original method and acceptance criteria to verify acceptability of the repaired weld.
4.5.4.8 If the original weld required post weld heat treatment, then it shall be heat treated after the repair using the method originally approved by COMPANY.
5.0 FABRICATION, ASSEMBLY AND ERECTION 5.1 General Piping
5.1.1 Piping shall be neatly installed with piping runs level, straight, plumb, square,
and parallel to platform column rows unless otherwise specified by the Technical Requirements or approved by COMPANY. Changes in direction shall generally
be made with 90o turns or rolls.
5.1.2 Piping terminations at pressure vessels and major equipment, such as pumps or
compressors, shall be installed so that mating flanges are parallel, concentric and in contact prior to bolting the piping in place. Flanges shall not require "springing" to insert gaskets. Piping shall not impose loads greater than that allowed by the equipment manufacturer, applicable code or Technical Requirement, whichever is more conservative.
5.1.3 Prefabricated pipe spools shall have a sufficient number of properly located field
welds to allow flanged connections to be installed without imposing excessive loads, moments or strain into the system.
5.1.4 The maximum offset allowed on pipe spools to be welded together shall be
1/16". Bolt holes in flanged joints shall have less than 1/8" offset. Hammering, jacking or other mechanical alignment methods shall not be acceptable.
5.1.5 Minimum spacing between circumferential weld joints shall be 2", or 6 times the
wall thickness of the pipe, whichever is greater, unless otherwise approved by COMPANY.
5.1.6 Couplings or other weld-on type branch connections and fittings shall not be
located on a weld joint.
5.1.7 Flange bolt holes shall straddle normal horizontal and vertical center lines.
5.1.8 Miter welds shall not be acceptable unless approved by COMPANY.
5.1.9 A valved drain connection shall be provided by CONTRACTOR at all piping low
points regardless of whether or not a drain connection is indicated on the drawings. Piping drain valves shall be a minimum of 3/4" NPS and shall be provided with plugs or blind flanges, unless specified otherwise by the Technical Requirements.
5.1.10 A vent connection shall be provided by CONTRACTOR at all piping high points where gas may be trapped, regardless of whether or not a vent connection is indicated on the drawings. Vent connections shall be a minimum of 3/4" NPS and shall be provided with plugs or blind flanges, unless specified otherwise by the Technical Requirements.
5.1.11 Threads on threaded pipe and fittings shall be cut to ANSI B1.20.1 "Pipe Threads (Except Dry Seal) Specifications, Dimensions, and Gaging for Taper and Straight Pipe Threads Including Certain Special Applications."
5.1.12 Teflon tape or pipe dope shall be used on all threaded pipe joints, except for
those joints that are to be back welded. Teflon tape or pipe dope shall only be applied to the male thread of the joint.
5.1.13 Piping "as-built" dimensional tolerance with regard to final end-to-end dimensions (across the platform) and location of branches or appurtenances shall be plus or minus 1/8" linearly and plus or minus 2o angularly. Lines that are
designated as "sloped lines" shall maintain a positive slope in the direction specified.
5.1.14 For piping that is designated as "sloped," the total slope shall be as uniformly
distributed as practicable throughout the entire length of the line by shimming the pipe where necessary. After installation, shims shall be seal welded into place to prevent displacement and loss. Pipe shall be removed or lifted in place to permit surface preparation and coating of the shims.
5.1.15 An inert gas arc welding process (TIG or MIG) shall be used on the root pass of
welded joints on compressor suction piping that are not accessible for internal inspection and cleaning. The remaining passes may be welded by the Shielded Metal-Arc Welding (SMAW) process.
5.2 Pipe Supports
5.2.1 Pipe supports shall be designed, fabricated and installed in accordance with the
AISC "Manual of Steel Construction" and the AWS D1.1 "Structural Welding Code." Pipe supports shall be designed to withstand the load conditions specified by the Technical Requirements.
5.2.2 All piping shall be adequately supported and securely clamped to minimize
vibration and prevent unnecessary strain on the piping system, including valves, instrumentation, meters and equipment. In general, piping shall be supported as required by the Technical Requirements; namely the approved piping drawings. However, during piping erection additional supports are often deemed necessary to meet the Technical Requirements, and shall be provided by CONTRACTOR at no additional cost to COMPANY.
5.2.3 Pipe supports shall be installed such that no piping butt welds rest on the
support.
5.2.4 Pipe support structures shall be of welded construction. Bolted construction
shall be allowed by COMPANY only if welded construction is prohibited by shipping, handling, installation or maintenance considerations.
5.2.5 Pipe supports shall be welded to main structural beams of the platform, deck, module or skid. Pipe supports shall not rest upon or be supported by grating, deck plate or other non-structural elements. Beams shall be fabricated so that after erection any minor camber as a result of rolling or shop assembly will be upward.
5.2.6 Holes for bolted connections shall be 1/16" larger diameter than the bolts. All
holes shall be drilled prior to the application of any protective coatings. Torch cut holes shall not be accepted by COMPANY.
5.2.7 Unless otherwise specified in the Technical Requirements, pipe shall be
clamped to pipe supports using bichromated cadmium plated "U" bolts complete with rubber sleeves. Neoprene rubber pads, a minimum of 3/8" thick, shall be provided between the pipe and support for all pipe 8" NPS and smaller. All "U" bolts shall be double nutted with bichromated cadmium plated nuts.
COMPANY shall not accept galvanized bolting, including studs, bolts, cap screws, jacking bolts, nuts, washers, "U" bolts, etc., on piping systems, and in particular, not on stainless steel piping systems.
5.2.8 Where COMPANY approval has been granted to weld supports directly to
piping, the following requirements shall apply:
a. The pipe support shall be welded to the pipe in a manner that will minimize penetration into the pipe and will minimize local stresses induced in the piping. Recommend procedures include SMAW (in the downhill direction) or GMAW.
b. Undercutting shall not be accepted under any circumstances.
c. The pipe support material shall be compatible with the pipe or fitting material. Preheating, welding and heat treatment of the support to the pipe shall be in accordance with the welding requirements for the pipe.
5.2.9 CONTRACTOR shall demonstrate the acceptability of pipe support welding
procedures prior to commencement of work. All pipe support welds shall be subject to visual or NDE inspection and acceptance by COMPANY.
5.2.10 Unless specified otherwise by the Technical Requirements, pipe supports shall
be installed so that bolted spool pieces can be removed for maintenance without cutting.
5.2.11 Stiffeners shall be fitted accurately, neatly and tightly to transmit bearing loads.
Stiffener ends shall be milled or ground smooth to conform to the geometry of the member when fillet welds are utilized. Otherwise, stiffener ends shall be beveled to ensure 100% fusion in the root of the weld.
5.2.12 All pipe support welding shall be full seal welds as a minimum. Seal welds shall
be placed at all contact edges of plate and on the supporting flanges of beams, tees, etc., and the flat legs of angles. Surfaces inaccessible for coating shall be sealed by boxing-in with plate. Skip or stitch welding shall not be acceptable under any circumstances.
5.2.13 Splices in structural shapes and pipe shall be full penetration welds to provide 100% joint efficiency. Splicing tolerances shall comply with the AISC "Manual of Steel Construction."
5.2.14 Splices in structural pipe shall not be closer together than one pipe diameter, or
3'-0", whichever is greater. For beams, splices shall not be closer together than twice the depth of the beam, or 3'-0", whichever is greater.
5.2.15 If a beam spans a support, the beam shall not be spliced in the middle quarter
of the span, in the eighth of the span nearest the support, or over the support.
5.2.16 Cantilevered beams shall not be spliced closer to the support than one-half the
cantilever span length.
5.2.17 As a minimum, pipe supports fabricated as "ship loose" for installation by COMPANY (or Others) shall be test-fitted to confirm fit-up, then coated with primer and color-coded with paint marks to facilitate field assembly. Paint marks shall be at least 2" high unless limited by the size of the member to be marked. Marks shall be applied to members in a protected location where they will not be evident upon completion of installation. Paint mark color shall be in sharp contrast with the primer paint, and shall be compatible with the primer and finish paints specified by the Technical Requirements. Paint shall be durable for exposure to normal atmospheric conditions for a minimum of 6 months.
6.0 POST WELD HEAT TREATMENT 6.1 General
6.1.1 Post weld heat treatment (PWHT) shall be in accordance with ANSI B31.3
"Chemical Plant and Petroleum Refinery Piping" except as modified by the Technical Requirements.
6.1.2 All carbon steel piping with a wall thickness greater than 3/4" shall be post weld
heat treated at 1100 to 1200°F for 1 hour per inch of nominal wall thickness, but
in no case less than 1 hour.
6.1.3 During heat treatment, all piping shall be properly supported to prevent warping
or deterioration.
6.1.4 Machined surfaces shall be protected by suitable paint or compound to prevent
damage from scaling during heat treatment.
6.1.5 Welding shall not be allowed on piping after post weld heat treatment, unless
specifically authorized in writing by COMPANY and in accordance with ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping."
6.1.6 When post weld heat treatment of stainless steel piping is required, it shall be at
1550 to 1625°F for 1 hour per inch of nominal wall thickness, but with a 1 hour
minimum. Cooling from heat treatment temperatures shall be in still air outside the furnace.
6.2 Exothermic Heat Treatment
6.2.1 Heat treatment may be by the exothermic method if the exothermic materials
are designed for the application and if consideration is given to the thickness of the piping and the configuration of components being heat treated.
6.2.2 CONTRACTOR shall demonstrate successful past experience in using the
materials on the specified size and wall thickness of pipe.
6.2.3 The process and materials for exothermic treatment shall be subject to approval
by COMPANY.
7.0 QUALITY ASSURANCE AND QUALITY CONTROL 7.1 General
7.1.1 CONTRACTOR shall be responsible for all aspects of quality assurance and
quality control (QA/QC) during all phases of the work, including visual inspection of all weld preparation, joint fit-up, welding and completed assemblies. Corrections shall be made as necessary during joint fit-up and weld preparation to ensure that sound welds can be achieved by the welding process employed. All welds shall be visually inspected after the work is completed.
7.1.2 COMPANY reserves the right to inspect, or for an authorized representative to
inspect the work at any time during fabrication and to have access to all test records and results.
7.1.3 CONTRACTOR shall afford COMPANY, free of charge, all necessary and
reasonable information and use of facilities needed for determining that piping systems are being furnished in accordance with the Technical Requirements. COMPANY inspection shall not relieve CONTRACTOR of responsibility for all examinations necessary to assure compliance with the Technical Requirements.
7.1.4 Should the work of a fitter, welder or welding operator be judged unsatisfactory
by COMPANY, the fitter, welder or welding operator shall be removed from the work by CONTRACTOR. The fitter, welder or welding operator may be reassigned only after the completion of satisfactory re-qualification tests and approval of COMPANY.
7.2 Radiography
7.2.1 Radiographic inspection shall be performed by a qualified third party
SubContractor. Self-examination by CONTRACTOR shall not be acceptable to COMPANY. Technicians shall be qualified to American Society of Nondestructive Testing (ASNT) Recommended Practice No. SNT-TC-1A "Nondestructive Testing Qualification and Certification." Inspectors responsible for grading and interpretation of radiographs shall be Technician Level II or III certified by ASNT SNT-TC-1A, and helpers shall be SNT-TC-1A Level I certified as a minimum.
7.2.2 Unless specified otherwise in the Technical Requirements, the following
minimum percentages of welds in each pipe class shall be radiographically inspected:
ANSI 150 10% ANSI 300 10% ANSI 600 10% ANSI 900 20% ANSI 1500 20% ANSI 2500 100% API 3000 100% API 5000 100% API 10000 100%
7.2.3 In addition to the above requirements, 100% of the welds in hydrocarbon
services shall be radiographically inspected. This shall include all lines classified as process lines, instrument gas, utility gas, diesel fuel, fuel gas, blanket gas (if hydrocarbon), utility oils, and pipelines as defined in the Technical Requirements.
7.2.4 In addition to the above requirements, 100% of all welds in hydrogen sulfide
(H2S) services shall be radiographically inspected, including welds other than
girth butt welds if weld geometry permits. Where weld geometry precludes radiographic examination, the weld shall be examined by the magnetic particle or liquid penetrant method as outlined in ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping."
7.2.5 Where radiography is specified to be less than 100%, the radiography shall be a
"random examination" as opposed to a "spot examination." Welds selected to be examined shall be evenly distributed between all pipe spools and welders in so much as reasonably possible. Concurrence of COMPANY shall be obtained on the selection of welds to be examined.
7.2.6 Production welding quality shall be established at the beginning of the work by
radiographic inspection. Welds selected for examination shall be representative of each welder and welding procedure, and shall be taken shortly after completion of the weld, but not within 24 hours. The percentage of radiographed welds shall be evenly distributed among all welders.
7.2.7 Radiographic technique shall produce maximum contrast and good definition of
penetrameter holes and shall obtain a film density of 1.7 to 3.5 in the weld image. Fluorescent intensifying screens shall not be used. All penetrameters shall be shimmed to compensate for weld reinforcement.
7.2.8 All radiographic film shall be identified with a weld number traceable to the weld
location. COMPANY shall not accept any radiographs and/or fabricated items without proper identification of the weld films.
7.2.9 COMPANY reserves the right to require additional radiographs. Should
additional repairs be required, then CONTRACTOR shall bear all costs for the additional radiographs and repairs. Should repairs not be required, then COMPANY will reimburse CONTRACTOR reasonable costs for the additional radiographs.
7.2.10 If less than 100% of the welds are examined, for each unacceptable weld the
and including radiography on every weld if necessary. All costs associated with additional radiography as a result of unacceptable welds shall be at CONTRACTOR's expense.
8.0 FLUSHING AND HYDROSTATIC TESTING 8.1 General
8.1.1 Upon completion of fabrication and inspection, each piping system shall be
flushed and then hydrostatically pressure tested in accordance with ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping" to verify the integrity of the materials and weldments prior to commissioning and placing the systems in service. All piping systems shall be hydrostatically tested, including systems designed for 15 psig and less without regard to the design temperature. Test requirements may waived only by COMPANY.
8.1.2 CONTRACTOR shall ensure that all portions of the system are tested.
CONTRACTOR shall be responsible for ensuring that test pressures required by paragraph 8.3.1 do not result in damage to any piping or system components, including attached equipment and instrumentation.
8.1.3 All fabrication, erection and inspection work, including but not limited to welding,
nondestructive examination, heat treatment, etc. shall be completed and accepted by COMPANY prior to flushing and hydrostatic testing. The application of paint, insulation or any other pipe coverings shall not start until successful completion of hydrostatic testing.
8.1.4 CONTRACTOR shall be responsible for performing flushing and hydrostatic
testing in accordance with the Technical Requirements. Use of SubContractor-CONTRACTOR(s) shall require COMPANY approval. All tests shall be performed at a location suitable for performing the tests. Test equipment including pumps, gauges, recorders, and other items shall be located in the same area, if possible. Hydrostatic testing shall not be allowed outdoors during inclement weather conditions.
8.1.5 CONTRACTOR shall prepare detailed hydrostatic test procedures for each
hydrostatic test, including a pressure test flow diagram to define and record the extent of each test. The procedures shall be submitted for COMPANY review and approval a minimum of two weeks prior to hydrostatic testing. The diagrams shall clearly detail the extent of the systems to be tested, the valves to be opened, and the equipment and instrumentation to be removed, isolated by blanking with blind flanges, or otherwise protected. Piping classification breaks shall be clearly marked on all pressure test diagrams. A copy of the mechanical flowsheets may be marked to produce the required pressure test flow diagrams.
8.1.6 CONTRACTOR shall test as much of the piping system as possible at one time
without exceeding the maximum allowable test pressure of the weakest element in the system.
8.1.7 If a portion of a piping system cannot be hydrostatically tested because the
presence of water is unacceptable, a notation shall be made on the pressure test flowsheets indicating that hydrostatic testing is prohibited. The affected
portion shall be isolated and tested pneumatically in accordance with Section 9.0 below.
8.1.8 The test fluid normally shall be clean, fresh potable water with a suitable corrosion inhibitor added by CONTRACTOR. Test fluid shall not contain suspended solids which may possibly plug orifices or small lines. For stainless steel piping systems the chloride content of the water shall not exceed 30 ppm. Alternately, a hydrotest medium such as diesel fuel or kerosene may be proposed for COMPANY consideration.
8.1.9 The temperature of the hydrotest fluid shall not be less than 60°F. If the fluid
temperature is likely to fall to 32°F during the test period, then glycol or another COMPANY approved antifreeze shall be added to prevent freezing.
8.1.10 A preliminary test schedule shall be submitted with CONTRACTOR’s work plan,
and updated periodically during fabrication. This schedule shall list proposed test dates for all piping systems and note deadlines for submittal and approval of detailed test procedures for each piping system.
8.1.11 CONTRACTOR shall provide COMPANY a minimum of one week notice for all
flushing and hydrostatic testing. The piping system to be flushed and tested shall be detailed in the notice, including the specific lines and equipment.
8.1.12 Preliminary or unofficial tests may be performed at the discretion of
CONTRACTOR, provided that COMPANY is notified and afforded the opportunity to witness the tests.
8.2 Preparation for Testing
8.2.1 CONTRACTOR shall ensure that flushing and tests do not result in damage to
equipment and instrumentation. Equipment and in-line instrumentation that may be damaged by hydrostatic testing shall be isolated by blinds or plugs, or shall be disconnected from the piping system. This shall include, but not be limited to turbines, pumps, compressors, safety valves, turbine flowmeters and rupture discs. Mounted instrumentation shall be removed or isolated from the system during flushing and testing.
8.2.2 Restrictions that interfere with flushing, filling, venting or draining, such as orifice
plates and flow nozzles shall not be installed until the completion of testing. 8.2.3 After erection and prior to hydrostatic testing, all piping shall be thoroughly
flushed to remove weld slag, blast grit, dirt, sand, trash and other debris, and foreign materials. CONTRACTOR shall submit a detailed flushing procedure for approval by COMPANY, which shall be in accordance with the following:
a. Carbon steel piping shall be flushed with potable water. Stainless steel piping shall be flushed with potable or raw water with a chlorine content below 30 parts per million (ppm). Piping shall not be flushed with seawater without prior written approval from COMPANY.
b. Required flushing flowrates shall be determined based on pipe diameter and flow velocities. Velocities from 8 to 12 feet per second (fps) shall be required for lines up to 10" NPS. Larger diameter lines shall use the highest velocity reasonably possible, which shall be approved by COMPANY. Compressed
air may be injected into the water while flushing to increase turbulence and velocity. Drop flushing, the filling and draining of a piping system, does not constitute flushing and shall not be accepted.
c. Piping and piping systems which cannot be flushed with water (because the presence of water is unacceptable) shall be blown out with high pressure, high velocity air. This shall include instrument and utility air lines as a minimum.
d. Control valves, positive displacement meters, turbine meters, rotameters, and relief devices shall be removed from the piping system during flushing.
8.2.4 Valving, including ball, gate, globe, plug and butterfly valves shall be in the fully
open position during hydrotesting. Lines containing check valves shall have the pressure source located on the upstream side, or the check valves shall be removed from the line or blocked open for hydrotesting.
8.2.5 Expansion joints shall be hydrotested with the piping system to check the
restraining devices.
8.2.6 Control valves shall remain in the line for hydrotesting and shall be in the fully
open position. Valves that are normally closed shall be opened for hydrotesting using clean dry air. Valves shall not be jacked or forced open by CONTRACTOR.
8.2.7 Pressure control valves with internal passages between the process fluid and
the diaphragm shall be isolated from hydrotesting. External connections shall be disconnected or blocked during hydrotesting, and the diaphragm pressure shall be bled off.
8.2.8 Hydrostatic testing shall be performed with the "in service" type of gaskets, and
shall not utilize any gasket sealing compounds. New gaskets shall be installed on all connections that are broken after completion of the hydrotesting, or that must be reassembled after testing.
8.2.9 Temporary supports shall be installed as necessary to prevent sagging or
excessive stress on the piping system. Special consideration shall be given to supporting partially liquid packed or gas piping systems during flushing and hydrostatic testing. Particular attention shall be given to systems having spring or counterweight supports, and to systems containing expansion joints or loops.
8.2.10 Large diameter lines that are grouped together on common supports shall not
be simultaneously hydrotested if the weight of the test medium might overstress the supports.
8.3 Hydrostatic Leak Testing
8.3.1 Unless specified otherwise by the Technical Requirements, the minimum
hydrotest pressure for steel piping shall be in accordance with the following table:
Pipe Class Carbon Steel System: Stainless Steel System:
Rating: (psig) (psig)
Pipe Class Carbon Steel System: Stainless Steel System:
Rating: (psig) (psig)
ANSI 300 1,125 900
ANSI 600 2,225 1,800
ANSI 900 3,350 2,700
ANSI 1500 5,575 (Note 1) 4,500
ANSI 2500 9,275 7,500
API 3000 4,500 (Note 2) N/A
API 5000 7,500 (Note 2) 6,900 (Note 2)
API 10000 15,000 (Note 2) N/A
Note 1: For flanges 16" NPS and larger the test pressure shall be 4,500 psig. Note 2: CONTRACTOR shall confirm that all components in API 6A piping
systems are suitable for the specified hydrostatic test pressure prior to procurement. Components not suitable for the specified hydrostatic test pressure shall not be utilized by CONTRACTOR without prior, specific written approval of COMPANY.
Note 3: Refer to technical requirements for hydrostatic test pressure for duplex stainless steel.
8.3.2 Hydrostatic test pressures are for the new and cold condition, with test
temperatures of 100°F or less. For higher test temperatures, CONTRACTOR
shall be responsible for checking the piping system and determining the appropriate test pressure. The test pressure shall be selected such that the test shall not exceed 90% of the yield strength of the weakest component at the test temperature.
8.3.3 Hydrostatic testing shall be maintained for a minimum of 2 hours after
stabilization of pressure and temperature.
8.3.4 All hydrostatic tests shall be maintained for a sufficient period of time to check
for small seepage leaks. Upon successful completion of the hydrostatic test period, the piping system shall receive a final visual check for leaks.
8.3.5 Hydrostatic testing shall be performed with two separate pressure gauges and a
dual-pen (pressure and temperature) chart recorder. Pressure gauges and recorders shall have a pressure range of approximately twice the required test pressure.
8.3.6 All gauges and recorders shall have been dead-weight tested and certified
within 6 months of hydrostatic testing. The certifications shall be available for COMPANY review during all hydrostatic testing.
8.3.7 All vents shall be open during filling to ensure proper venting of all air or gases.
8.3.8 Test pressure shall not be applied against any closed valve. Skillets or blinds
shall be installed to protect valves that must remain in the closed position.
8.3.9 If the test liquid in the system is subject to thermal expansion, CONTRACTOR
surveillance throughout the test period by a suitably qualified person may be considered.
8.3.10 Recorder charts shall depict one system test only. Charts shall be signed and
dated by CONTRACTOR and COMPANY upon completion of the test to certify that the test was performed.
8.3.11 CONTRACTOR shall collect, record and maintain all information required for
complete test records. As a minimum, test records shall include the following information:
a. Test Date with Start and Finish Times
b. Piping Line and Equipment Numbers (or pressure test flow diagram number) c. Design Pressure and Temperature
d. Minimum Test Pressure and Hold Time
e. Test Pressure & Temperature Recording Chart f. Water Chloride Content (stainless steel piping) g. Test Medium (if not water)
h. Applicable Remarks Concerning Defects
i. CONTRACTOR and COMPANY Approval Signatures
8.3.12 Leaks found during testing shall be repaired and the piping system retested in
accordance with the Technical Requirements. COMPANY reserves the right to require alternate pressure tests should a piping system fail the standard pressure test.
8.4 Post-Test Requirements
8.4.1 All piping systems, including equipment and instrumentation included in the
testing shall be thoroughly drained, cleaned and dried upon completion of testing.
8.4.2 After completion of hydrostatic testing and COMPANY release, the system shall
be de-pressurized by opening the de-pressuring valve on the test rig.
8.4.3 The system shall be completely vented and then drained of the hydrotest fluid.
Particular attention shall be paid to venting during draining to avoid producing a vacuum in the system and to allow complete drainage. Special attention shall be given to equipment, instrumentation and piping system low points where water may be trapped, such as valve bodies or control valve stations, to ensure complete drainage.
8.4.4 Lines and equipment shall be cleared of all debris after drainage, and then shall
be dried by blowing warm air through the system. In particular, strainers shall be emptied and cleaned. Alternate drying methods may be employed by CONTRACTOR if approved by COMPANY, such as vacuum drying.
8.4.5 Soft seated valves, particularly ball valves, shall not be operated until the lines
have been thoroughly cleaned and dried.
8.4.6 All vent and drain valves shall be blinded or plugged after completion of hydrotest, cleaning and drying.
8.5 Leak Repair and Re-testing
8.5.1 CONTRACTOR shall be responsible for all costs associated with repair of
deficiencies resulting from CONTRACTOR’s work or CONTRACTOR-supplied equipment or materials. Costs shall include, but not be limited to development of repair procedures, repairs, inspection and testing, radiography, stress relief (if applicable) and hydrostatic testing necessary to correct the deficiency to COMPANY’s satisfaction.
8.5.2 CONTRACTOR shall advise COMPANY of all defects in writing, and shall
submit a proposal with recommended repair procedures to COMPANY for approval prior to starting any repair work.
8.5.3 Welds or portions of welds that leak during hydrostatic testing and that have not
been radiographed previously shall be radiographed at the affected areas before being cut out and rewelded.
8.5.4 After repair, the welds or portions of welds shall be radiographed again. The
hydrostatic test shall be performed again to verify the repairs, unless specifically approved otherwise by COMPANY in writing.
9.0 PNEUMATIC TESTING 9.1 General
9.1.1 Pneumatic testing may be substituted for hydrostatic testing only with prior written approval by COMPANY, and if:
a. Hydrostatic testing is totally impractical, or
b. Piping or attached equipment might be damaged by water and no alternative exists to avoid damage, or
c. Even a small amount of water left in a system could contaminate or injure the system, such as in a refrigerant or aviation fuel system.
9.1.2 For safety reasons, the volumes of systems being pneumatically tested shall be
kept to a minimum.
9.1.3 Unless otherwise specified, pneumatic tests shall utilize clean, dry air or
nitrogen as the test medium. If air is utilized to test instrument air lines it shall also be oil-free.
9.1.4 If a test requires a closure joint (flanged, screwed, or welded) for blocking purposes, the integrity of the repaired or reworked joint shall be tested as applicable.
9.1.5 Access to pneumatic test areas shall be restricted to personnel absolutely
required to conduct the tests.
9.2 Pneumatic Leak Testing
9.2.1 Pneumatic test pressures shall be in accordance with the following table, except
that the maximum hoop stress during testing shall not be greater than 50% of the specified minimum yield strength as noted in 49 CFR 192 "Transportation of Natural and Other Gas by Pipeline: Minimum Federal Safety Standards":
Pipe Class Carbon Steel System: Stainless Steel System:
Rating: (psig) (psig)
ANSI 150 315 300 ANSI 300 815 790 ANSI 600 1,630 1585 ANSI 900 2,440 2375 ANSI 1500 4,075 3960 ANSI 2500 6,785 6600
9.2.2 CONTRACTOR shall be responsible for developing appropriate procedures for
pneumatic leak testing. Procedures shall be submitted for COMPANY review and approval, and shall incorporate the following as a minimum:
a. The pneumatic test pressure shall start at 25 psig.
b. The test pressure shall be increased gradually in increments of 15 psid to provide time for stress in the piping to equalize. The gradual increase also provides sufficient time to check for leaks.
c. After the full test pressure has been reached and the temperature has stabilized, all piping welds and connections shall be inspected for leaks, after which the pressure shall maintained for a minimum of 1 hour, and the piping welds and connections inspected for leaks again to complete the test.
9.2.3 All welds and threaded connections shall be inspected for leaks with a
soapsuds test. All flanged connections shall be masked with tape and a small pinhole punched in the tape to facilitate the identification of leaks.
9.2.4 If both hydrostatic and pneumatic pressure testing may damage the piping
system, alternate testing methods may be performed with prior written approval of COMPANY. Alternate testing methods shall include the following:
a. Butt welds shall be 100% radiographed in accordance with ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping."
b. Welds, other than butt welds shall be liquid penetrant and magnetic particle tested in accordance with the ASME "Boiler and Pressure Vessel Code" - Section V "Nondestructive Examination" - Article 6 and Article 7 respectively. If heat treating is required, the above examinations shall be performed after completion of heat treating. Limitations or imperfections found as a result of the tests shall be stated as required by ANSI B31.3 "Chemical Plant and Petroleum Refinery Piping."
10.0 CLEANING, DESCALING AND PASSIVATING CARBON STEEL PIPING 10.1 General
10.1.1 CONTRACTOR shall clean, descale (pickle) and passivate carbon steel piping
systems as specified by the Technical Requirements, as well as where recommended by equipment manufacturer's. In general, any piping service in which scale can potentially cause damage to downstream equipment shall be cleaned, descaled and passivated by CONTRACTOR. As a minimum, all piping in the following services shall be cleaned, descaled and passivated:
•Compressor Suction Piping (from the Scrubber, Filter or K.O. Drum)
•Compressor Interstage Coolers, and Suction and Bypass Piping
•Compressor Suction Pulsation Dampeners
•Lube Oil Piping
•Seal Oil Piping
•Control Oil Piping
•Hydraulic Oil Piping
•Fuel Gas Piping to Equipment Drivers
•Diesel Fuel Piping to Equipment Drivers.
10.1.2 The cleaned, descaled and passivated pipe shall be free of all scale, rust, weld
flux, oil, grease and other foreign materials and shall be equivalent to a Steel Structures Painting Council SP-8 "Acid Pickling" or SP-6 "Commercial Blast Finish" surface. All weld flux, metal shavings, coatings, sand, dirt and other foreign materials not soluble in chemical cleaning solutions shall be removed prior to fabrication or cleaning operations.
10.1.3 CONTRACTOR shall propose the cleaning, descaling and passivation method,
unless otherwise specified by COMPANY. However, the method shall be approved by COMPANY prior to the start of work.
10.2 Acid Pickling and Passivation
10.2.1 General
10.2.1.1 CONTRACTOR shall be responsible for acid pickling (descaling) and
passivation, including the selection of pickling solutions and inhibitors. CONTRACTOR shall properly control the pickling solution to avoid excessive corrosion of the metal by the pickling solution. CONTRACTOR shall ensure that test samples (corrosion coupons) representative of all materials in the piping system are exposed to the pickling solution. Exposure of the test coupons shall be for the entire duration to accurately monitor the corrosive effect of the solution on the piping system. A typical pickling procedure shall be as outlined in the following sections.
10.2.1.2 Pickling solutions shall not be allowed to contact any parts of process equipment or instrumentation.
10.2.1.3 Pickling solutions shall not be allowed to contact valves, check valves, relief
valves, meters, instrument tubing, strainers, or other piping components that contain elastomer seals, chrome or nickel plating, or galvanized coatings.
10.2.2 Precleaning and Rinsing
10.2.2.1 CONTRACTOR shall circulate a 2% (wt.) trisodium phosphate solution with
wetting agent (surfactant) to remove grease and oil films from the pipe before pickling. Solution shall be mixed in accordance with the manufacturer's instructions, and the pipe treated for 1 to 2 hours at 140 to 160°F. All oil and grease shall be removed before the start of pickling.
10.2.2.2 After removing the precleaning solution, the system shall be rinsed with clean, potable water until the pH of the effluent rinse is within one pH of the fresh rinse water.
10.2.3 Acid Pickling (Descaling)
10.2.3.1 The system shall be pickled (descaled) with one of the following solutions:
a. Sulfuric acid (10%) for 4 to 6 hours at 150°F. When mixing acid with water, CONTRACTOR shall ensure that the acid is added to the water, not water added to acid.
b. Hydrochloric acid (7%) for 4 to 6 hours at 150°F. Note that all alloy trim valves shall be temporarily removed to avoid pitting of the trim. HCl is an acceptable alternative when valves can be temporarily removed.
c. Inhibited ammoniated citric acid (3% to 5%) for 6 hours at 180 to 200°F. Citric acid and inhibitor shall be mixed into the water first, and the ammonia added to adjust the pH to between 4 and 5. Use of ammoniated citric acid allows both pickling and passivating with the same solution, eliminating the steps required in Section 10.2.4 below.
10.2.3.2 The system shall be agitated as necessary during circulation to flush out all
loose scale. An inhibitor shall be used during pickling in accordance with the manufacturer's instructions.
10.2.3.3 Acceptable inhibitors shall be as follows:
•Armohib 31 for sulfuric or citric acid
•Rodine #213 or #214 for hydrochloric acid.
10.2.3.4 After pickling for the required time period the acid solution shall be drained under a nitrogen purge.
10.2.3.5 The system shall then be rinsed again in accordance with Section 10.2.2.2 above. The rinse shall be removed under a nitrogen purge. When using an ammoniated citric acid, this step may be deleted.
10.2.4 Neutralization
10.2.4.1 A neutralizing solution of 2% soda ash (sodium carbonate) shall be circulated to
remove all traces of acid from the system. The solution shall be circulated for a minimum of 1 hour at 120°F, and then drained under a nitrogen purge. When using an ammoniated citric acid, this step may be deleted.
10.2.4.2 After neutralizing, the system shall be rinsed with water until all traces of acid
and neutralizing solution have been removed, and then drained under a nitrogen purge. When using an ammoniated citric acid, this step may be deleted.
