TABLE OF CONTENT 1 PROJECT INTRODUCTION ... 5 1.1 SCOPE OF DOCUMENT ... 7 1.2 DEFINITION ... 7 1.3 ABBREVIATION ... 7 2 REFERENCES ... 8 2.1 PROJECT DOCUMENTS ... 8 2.2 COMPANY STANDARDS ... 8 2.3 CODES AND STANDARDS ... 8 2.4 SYSTEM OF UNITS ... 9 3 GENERAL REQUIREMENTS ... 10 4 CONCRETE COATING MATERIALS ... 11 4.1 CEMENT ... 11 4.2 AGGREGATES ... 11 4.3 WATER ... 12 4.4 ADDITIVES ... 12 4.5 REINFORCING STEEL ... 12 4.6 WELDED STEEL WIRE MESH... 13 4.7 STEEL CAGE TYPE ... 13 5 RECEIPT, HANDLING AND STORAGE OF BARE PIPES ... 14 6 CONCRETE COATING APPLICATION ... 15 6.1 VISUAL AND HOLIDAY INSPECTION OF 3‐LAYER PE COATED PIPES ... 15 6.2 PLACEMENT OF REINFORCEMENT STEEL ... 15 7 APPLICATION OF COATING MATERIALS ... 16 7.1 PREPARATION OF THE CUTBACK AREA ... 16 7.2 FINISHING OPERATIONS WITHIN CONCRETE COATING PLANT ... 16 7.3 CURING ... 17 7.3.1 WATER CURING ... 17 7.3.2 STEAM CURING ... 18 7.3.3 CURING BY SEALING COMPOUNDS ... 18
7.3.4 CURING UNDER POLYETHYLENE WRAPPING ... 18 7.3.5 FOG CURING ... 19 8 INSPECTION AND TESTING ... 20 8.1 STACKING OF 3‐LAYER PE COATED PIPES ... 21 8.2 CONTROL, IDENTIFICATION AND SEGREGATION OF 3‐LAYER PE COATED PIPES ... 22 8.3 DELIVERY AND STORAGE OF CONCRETE COATING RAW MATERIALS ... 22 8.4 TEST TO BE PERFORMED ON CONCRETE COATING MATERIAL UPON RECEIPT ... 23 8.4.1 SIEVE ANALYSIS AND CLEANLINESS CONTROL OF AGGREGATES ... 23 8.4.2 STEEL REINFORCEMENT WIRES DIMENSIONAL CONTROL ... 23 8.4.3 MIXING WATER CHEMICAL ANALYSIS ... 23 8.5 VERIFICATION OF CALIBRATION OF THE TEST INSTRUMENTS ... 24 8.5.1 HOLIDAY DETECTOR ... 24 8.5.2 PIPE WEIGHING SCALES ... 24 8.6 VISUAL AND HOLIDAY INSPECTION OF THE 3‐LAYER PE COATED PIPES ... 24 8.7 CONCRETE COATING MIX CONTROL ... 25 8.8 CONCRETE COATING MIX TEMPERATURE MEASUREMENT ... 25 8.9 WATER‐CEMENT RATIO CHECK ... 25 8.10 REINFORCING WIRE POSITION CONTROL ... 26 8.11 CONCRETE COATING APPLICATION CONTROL ... 26 8.12 MEASUREMENT OF EXTERNAL DIAMETER OF APPLIED CONCRETE ... 26 8.13 CUTBACK CONTROL ... 27 8.14 WEIGHING OF FRESHLY CONCRETE COATED PIPE... 27 8.15 CALCULATION OF NEGATIVE BUOYANCY ... 27 8.16 VISUAL INSPECTION OF APPLIED CONCRETE ... 28 8.16.1 SURFACE FALL‐OUTS (SPALLING) OF FRESHLY CONCRETE COATED PIPES ... 29 8.16.2 CONCRETE COATING DAMAGES ON FRESH AND HARDENED CONCRETE ... 29 8.16.3 CRACKS ... 29 8.17 ELECTRICAL RESISTANCE BETWEEN STEEL REINFORCEMENT AND THE PIPE ... 30 8.18 CONTROL OF CURING PROCESS ... 30 8.19 CONTROL OF STACKING OF PIPES DURING THE CURING PROCESS ... 30
8.20 CONTROL OF MARKING ON CONCRETE COATED PIPES ... 30
8.21 CONTROL OF MARKING ON CONCRETE COATING REPAIR ... 31
8.22 DETERMINATION OF FACTOR ALPHA IN THE FORMULA FOR CALCULATION OF NEGATIVE BUOYANCY ... 31 8.23 COMPRESSION STRENGTH TEST CUBES ... 31 8.24 COMPRESSION STRENGTH CORE SAMPLES ... 32 8.25 DETERMINATION OF THE TIME FOR STACKING OF PIPES IN MORE THAN ONE LAYER ... 33 8.26 WATER ABSORBTION TEST ... 34 8.27 ADHESION BETWEEN THE 3‐LAYER PE COATING AND CONCRETE COATING ... 34 8.28 IMPACT TESTING ... 35 8.29 STACKING OF CURED CONCRETE COATED PIPES... 36 8.30 LOAD OUT INSPECTIONS ... 37 9 3‐LAYER PE COATING REPAIR ... 38 10 CONCRETE COATING REPAIR AND STRIPPING OF CONCRETE COATED PIPES ... 40 11 PIPE MARKING ... 42 12 STORAGE, HANDLING AND TRANSPORTATION OF CONCRETE COATED PIPES ... 43 13 DOCUMENTATION ... 45 13.1 GENERAL REQUIREMENTS ... 45 13.2 TECHNICAL DOCUMENTATION TO BE SUBMITTED DURING THE BIDDING PHASE ... 45
13.3 TECHNICAL DOCUMENTS TO BE SUBMITTED AFTER AWARD OF THE CONTRACT TO SUBCONTRACTOR ... 46 13.4 FINAL TECHNICAL DOCUMENTATION ... 47 13.5 CONTENT OF PARTICULAR TECHNICAL DOCUMENTS ... 48 13.5.1 CONCRETE COATING APPLICATION PROCEDURE ... 48 13.5.2 INSPECTION AND TEST PLAN ... 49 13.5.3 DAILY PRODUCTION REPORT ... 49
1
PROJECT INTRODUCTION
NC3 and NC8 are gas fields located in Block SK 316, approximately 180km North of Bintulu, Sarawak with water depth ranging approx. between 70m – 105m. NC8 field is located approximately 7km South East on NC3 field. The nearby riser facility E11RC is located approximately 80 km South West of NC3. The existing trunk line connecting E11RC to shore TL 6 is available and provisioned for in this gas field development. The locations of NC3, NC8 and nearby facilities are illustrated in Figure 1‐1 below. Figure 1‐1 Location of Project Gas from NC3 and NC8 fields are the main feed gas supplier into the PETRONAS LNG Complex Train 9 near Bintulu which is expected to be ready for start‐up in December 2015.The scope demarcation between upstream and downstream facilities is as described below in Figure 1‐2.Figure 1‐2 Upstream and Downstream Scope Demarcation
The development of NC3 and NC8 fields is envisaged to be in complex‐type configuration. NC3 will become a hub comprising of a Central Processing Platform (CPP) with living quarters and a bridge‐linked Wellhead Platform (WHP). Another WHP is to be installed at NC8; it will be tied‐back to NC3 via an inter‐field subsea pipeline. Though compression may not be required at the beginning of production, the need for gas compression is anticipated after approximately four (4) years. Hence the provision for future compression facilities and mercury removal facilities shall be considered as part of this FEED work for the NC3 CPP.
Figure 1‐3 Overall Development Concept
A new subsea pipeline connecting NC3 and E11RC will be installed to deliver the processed gas and the spiked dehydrated condensate. Due to incompatibility of this gas quality with the existing gas supply at the riser, a dedicated manifold at E11RC may be required to accommodate this tie‐in. This is to ensure that the gas from NC3 and NC8 fields do not contaminate the entire network to shore. As such, modification will be required to convert the existing TL 6 to be dedicated for gas from NC3 and NC8.
The future trunk line (TL 7) may be required in the future should TL 6 no longer be fit for service.
The processed gas and dehydrated condensate will be separated at onshore receiving facilities prior to being introduced into LNG Plant Train 9.
1.1 SCOPE OF DOCUMENT The purpose of this document is to define the minimum requirements for concrete weight coating to be used for the following offshore rigid pipeline in the SK316 Development Project: 32” Offshore pipeline from NC3 WHP to E11RC Platform 32” Offshore pipeline from E11RC Platform to Onshore Beach Valve Location 20” Offshore pipeline from NC8 WHP to NC3 WHP (Diameter to be confirmed) 1.2 DEFINITION COMPANY PETRONAS Carigali Sdn Bhd CONTRACTOR SAIPEM SUBCONTRACTOR Party selected by COMPANY/CONTRACTOR responsible for
application of the concrete weight coating on PROJECT pipes in accordance with this specification and other contractual documents
MANUFACTURER Supplier of the raw materials or inspection and testing equipment required to perform the work
PROJECT FEED for SK316 Facilities ‐ Development of the NC3 and NC8 Gas Fields 1.3 ABBREVIATION FBE Fusion Bonded Epoxy N/A Not Applicable No. Number OD Outside diameter (external pipe diameter) PQT Pre‐Qualification Test 3LPE 3‐Layer Polyethylene 3LPP 3‐Layer Polypropylene CWC Concrete Weight Coating
2
REFERENCES
Unless otherwise stated, the latest issue of the below listed PTS COMPANY Specifications, Codes, Standards and Regulations shall apply. Equivalent alternatives may be offered; these shall be identified and mutually agreed on. 2.1 PROJECT DOCUMENTS DOCUMENT NAME /1/ 05‐SSPL‐BOD‐U‐0001 Pipeline And Riser Design Basis /2/ TBC Input for Pipeline Study /3/ 05‐GEN‐BOD‐B‐0001 Process Design Basis /4/ 05‐SSPL‐REP‐U‐0001 Steady State Pipeline Simulation Report /5/ 05‐GEN‐BOD‐Z‐0002 Corrosion Study Memorandum /6/ 05‐SSPL‐REP‐U‐0002 Pipeline Transient Analysis Report /7/ 05‐SSPL‐REP‐U‐0003 Pipeline Route Selection Report 2.2 COMPANY STANDARDS DOCUMENT NAME /8/ 31.40.00.20 Pipeline & Riser Engineering /9/ 31.40.30.30 Concrete coating of linepipe 2.3 CODES AND STANDARDS DOCUMENT NAME/10/ ISO 21809‐1 Petroleum and Natural Gas Industries ‐ External Coatings for Buried or Submerged Pipelines Used in Pipeline Transportation Systems ‐ Part 1: Polyolefin Coatings (3‐Layer PE and 3‐Layer PP).
/11/ BS EN 10288 Steel Tubes and Fittings for Onshore and Offshore Pipelines ‐ External Two Layer Extruded Polyethylene Based Coatings
/12/ ASTM C 150 Standard Specification for Portland cement
/13/ ASTM C 33 Standard Specification for Concrete Aggregates
/14/ ASTM A 810‐01 Standard Specification for Zinc‐Coated (Galvanized) Steel Pipe Winding Mesh
/15/ ASTM A 615 M Standard Specification for Deformed and Plain Carbon Steel Bars for Concrete Reinforcement
/16/ ASTM 185‐01 Standard Specification for Steel Welded Wire
Reinforcement, Plain, for Concrete
/17/ ASTM A 82‐01 Standard Specification for Steel Wire, Plain, for Concrete Reinforcement
/18/ ASTM C 309‐98 A Standard Specification for Liquid Membrane‐
Forming Compounds for Curing Concrete
/19/ ASTM C 171 Standard Specification for Sheet Materials for
Curing Concrete
/20/ ASTM C 39/C39 M‐01 Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens
/21/ ASTM C 617‐98 Standard Practice for Capping Cylindrical Concrete Specimens
/22/ BS EN 197‐1 Cement ‐ Part 1: Composition, Specifications and Conformity Criteria for Common Cements
/23/ BS EN 1008 Mixing Water for Concrete ‐ Specification for
Sampling, Testing and Assessing the Suitability of Water, Including Water Recovered from Processes in the Concrete Industry, as Mixing Water for Concrete
/24/ BS 4482 Cold Reduced Steel Wire for the Reinforcement of
Concrete Products‐ Specification
/25/ BS 4483 Steel Fabric for the Reinforcement of Concrete ‐
Specification
/26/ BS EN 12390‐2 Testing Hardened Concrete ‐ Part 2: Making and Curing Specimens for Strength Tests
/27/ BS EN 12390‐3 Testing Hardened Concrete ‐ Part 3: Compressive Strength of test Specimens
2.4 SYSTEM OF UNITS
The International Unit System (SI) shall be utilized throughout the project, unless otherwise highlighted. Any conversion shall be provided in parenthesis where applicable.
3
GENERAL REQUIREMENTS
For testing purposes specified in this Specification, the production shift shall be considered of maximum 12 hours depending on the SUBCONTRACTOR’s internal organization. In case SUBCONTRACTOR intends to work more than 12 hours per day, COMPANY/CONTRACTOR shall consider that the work is performed in more than one shift and the relevant testing frequency shall be respected as per this Specification. All SUBCONTRACTOR’s documents shall comply with the limitations of this Specification. SUBCONTRACTOR shall promptly inform COMPANY/CONTRACTOR of any need to make changes to these documents, which shall have to be specifically accepted by COMPANY, who has the right to require additional testing without additional costs.
Any technical deviations to this Specification shall be obtained by SUBCONTRACTOR only through a concession request format. In any case it is not allowed to insert any deviation from this Specification in any SUBCONTRACTOR’s document prior that this deviation has not been previously presented separately to COMPANY/CONTRACTOR and approved in written by COMPANY/CONTRACTOR.
Concession requests require COMPANY’s review and approval prior to implementation of the proposed changes. Pipes coated by implementing the technical changes prior to the COMPANY’s approval shall be rejected.
Prior to the commencement of the production and during the production, COMPANY shall reserve the right to perform audits in the SUBCONTRACTOR’s facilities.
COMPANY and COMPANY’s representatives shall be permitted by SUBCONTRACTOR the unlimited access to all SUBCONTRACTOR’s facilities related to the SUBCONTRACTOR’s scope of work for the PROJECT starting from the moment the work has been awarded to SUBCONTRACTOR until SUBCONTRACTOR has completed all of the obligations related to his scope of work in the PROJECT.
It is mandatory requirement for SUBCONTRACTOR’s coating facilities that all of the inspection activities according to the action points specified in inspection and test plans can be performed by inspectors from all involved Parties in safe manner for all personnel involved in these activities. In case the inspection activities cannot be safely performed for all persons involved in inspection (CONTRACTOR, SUBCONTRACTOR’s, COMPANY’s and Third Party’s personnel), SUBCONTRACTOR shall stop all of the activities at that particular inspection point and shall organize the work space in a manner that all activities can be performed in safe manner. All costs due to such stoppages shall be borne only by SUBCONTRACTOR.
4
CONCRETE COATING MATERIALS
The concrete coating applied on line pipes shall have the following nominal dry and cured concrete density of 3044 kg/m3. 4.1 CEMENT Unless otherwise specified in the Purchase Order, all cement used for the preparation of the concrete shall be “Portland Cement” conforming to the requirements of one of the following standards depending on the availability at the location where the concrete coating application shall be carried out: ASTM C 150 Type II and V; MS 522 standard; BS EN 197‐1 standard.All batches of cement shall be supplied to SUBCONTRACTOR with test certificate stating the compliance either with the ASTM C 150 (Type II and V) or BS 12 or EN 197‐1 standard which shall then SUBCONTRACTOR submit to COMPANY for review prior to its use.
The certificates must be presented to COMPANY’s review to verify that also the following mandatory requirements are met: that the content of alkali is < 0.6 %; that the content of tri‐calcium aluminate C3A is < 8 %. Cement that has hardened, partially set or lumpy will be rejected and shall be removed from the work site. Reground and graded cement shall not be used. Cement not meeting any single of above mentioned requirements shall not be used in the PROJECT. Cement shall be stored in covered areas or covered by plastic sheeting. 4.2 AGGREGATES The sand shall be of the silica type. Clayey and schistose sands shall not be used. Sand shall be stored in a manner to avoid contamination from soil or other foreign matter.
Heavy aggregates shall be made of crushed granite, or any other aggregate approved by the COMPANY/CONTRACTOR. Aggregates shall not be made from chalky or decomposed stone. In case high density concrete is required, SUBCONTRACTOR may add iron ore to the concrete coating mix.
All aggregates shall be certified according to ASTM C 33 standard with exception of grading.
SUBCONTRACTOR shall propose the grading of aggregates in the concrete mix which shall be confirmed during the Pre‐Qualification Test. However it is mandatory that all aggregates shall be of the size that 100% of their quantity will be able to pass 10 mm sieves.
All aggregates shall be washed and shall be free from injurious amounts of salts, alkali, organic impurities or deleterious substances such as oxides of lead and zinc that may affect the strength of the concrete.
Sampling and testing for cleanliness of aggregates shall be carried out for each delivery of each aggregate in accordance with ASTM C 33 standard and other standards referred in the ASTM C 33 standard.
During production the grading and cleanliness shall be checked at least once every three days from each stockpile and each new consignment for cleanliness and grading. The grading shall be as per the nominal values and tolerances specified by SUBCONTRACTOR and verified during the PQT. The test for cleanliness shall mean visual inspection for presence of any foreign material in tested sample beside the tested aggregate itself (wood, shells, or any other similar contaminant). SUBCONTRACTOR shall be responsible for proper storage of aggregates and all costs related to the COMPANY’s rejection of contaminated aggregate shall be borne by SUBCONTRACTOR. Different types of aggregates shall be stored separately in bins or well prepared areas, i.e. cobbled, paved or well compacted areas allowing adequate drainage of materials. 4.3 WATER Water used in concrete coating mix shall be fresh and shall comply with Appendix A of BS EN 1008.
Water shall be of potable quality and obtained from a public supply where possible. Water shall not be taken from a spring, well, lake or similar source unless test indicate its suitability. During the bidding stage of the PROJECT the SUBCONTRACTOR shall present the certificate for the mixing water used in the coating plant and the SUBCONTRACTOR shall provide the guaranty that the same water shall be used during entire SUBCONTRACTOR’s work in the PROJECT. 4.4 ADDITIVES Additives containing chlorides shall not be used in the concrete mix. The total quantity of chlorides within the concrete mix, calculated as free CaCl2, shall not exceed 0.4% of the weight of the cement. Water reducing agents for concrete may be used in the concrete mix. Air entraining agents shall not be used in the concrete mix. 4.5 REINFORCING STEEL The reinforcing steel may be used in the following forms: welded steel wire mesh (type WW‐C or type WW‐N as per the ASTM A 810‐01 standard); steel cage type. Chicken wire mesh and steel poultry netting are not allowed as the reinforcement material. The diameter of the reinforcing steel shall be selected in a manner that all of the following requirements are met: the minimum circumferential reinforcement shall be 0.5% of the longitudinal cross sectional area of the concrete coating; the minimum longitudinal reinforcement shall be 0.08% of the transverse cross‐sectional area of the concrete coating;
minimum diameter of the reinforcing wire for the welded steel wire mesh shall be 1.6 mm; minimum diameter for the reinforcing wire in the cage type shall be 3 mm. 4.6 WELDED STEEL WIRE MESH The welded steel wire mesh shall be galvanized. The only approved type of the reinforcing steel wire mesh are Type WW‐C and Type WW‐N as per the ASTM A 810‐01 standard. The physical and chemical properties of the wire and wire mesh shall be in accordance with the ASTM A 641 and ASTM A 810‐01 standard. 4.7 STEEL CAGE TYPE
The reinforcement shall be in the form of spirally wound cages having a continuous hoop wire with a number of straight longitudinal bars evenly spaced around the spiral and welded at each wire intersection. Alternatively, the continuous hoop wire may be replaced by single circumferential hoops. The material used shall ben hard drawn wire to BS 4482 or ASTM A 615 M (deformed), or to COMPANY/CONTRACTOR‐ approved equivalent standard. The welding of materials shall result in a steel fabric in accordance with BS 4483 or ASTM A 185. The diameter of the circumferential and longitudinal bars shall be calculated from the required percentage of reinforcing, with a minimum diameter of 3 mm. The spacing of the longitudinal bars shall be between 50 and 250 mm but not less than four longitudinal bars at approximately equal spacing shall be provided. The circumferential hoop spacing shall not be more than 100 mm. Cages shall have two hoops spaced 50 mm apart at each pipe end. The physical and chemical properties of the reinforcing wire and of the wire mesh shall be in accordance with the ASTM A 82‐01 (or ASTM A 615 M) and ASTM A 185‐01 standard.
5
RECEIPT, HANDLING AND STORAGE OF BARE PIPES
Pipes coated only with 3‐layer polyethylene shall be handled, stored and transported in a manner that the pipe steel and pipe coating shall not be damaged.
All foreign substances such as excessive dirt, debris of coating materials or any other foreign objects shall be removed from internal pipe surface before stacking of pipes or application of concrete coating.
Coated pipes can be handled using slings, lifting hooks padded with soft material with suitable spreader bars, forklifts having lifting forks padded with soft material, front loaders padded with soft material and vacuum lifting. Chains or wire ropes or any other device that may damage the pipe steel or pipe coating shall not be used. When more than one pipe is lifted, separate slings or hooks shall be used for each pipe. Pipes shall be picked up from the stacking point and at no time shall be dragged or rolled. Coated line pipe shall not be subjected to jar or impact and all pipe supports shall be padded. Pipe supports shall be spaced to avoid bending of line pipes. The coated line pipes shall always be stacked to avoid surface contact with the ground. The pipes shall be stacked on approved supports which shall be free of any material that could potentially damage the applied coating.
The stacking height of 3LPE/3LPP coated line pipes shall be limited to avoid damage of the coated line pipes due to the weight of other ones. The maximum number of stacking layers for the coated line pipes shall be calculated by SUBCONTRACTOR and relevant calculation showing calculation steps and results shall be submitted to COMPANY/CONTRACTOR for review and approval however, for safety reasons the maximum height of any stack shall be 3 m. In case SUBCONTRACTOR does not provide any calculation note related to stacking of coated pipes acceptable for COMPANY/CONTRACTOR, the coated pipes shall be stacked in maximum 4 rows.
The stacks of coated pipes shall be separated for each of the following combinations: pipe nominal OD x pipe nominal wall thickness.
The line pipes shall be stacked at a slight angle to allow drainage of any rainwater.
The coated pipes shall not be stacked below and near electrical lines or near any facility which may increase residual magnetism in the pipes (at all times it shall be kept the minimum distance of 30 m between the stored pipes and any electrical cable measured from the vertical projection to the ground of the nearest electrical cable).
In case it is detected disbondment of the 3‐layer PE coating from the pipe at the coating edges when the coated pipes are stacked either before or during the load out operation, that particular pipe shall be rejected and the 3‐layer PE shall be stripped and re‐applied at SUBCONTRACTOR’s cost.
6
CONCRETE COATING APPLICATION
6.1 VISUAL AND HOLIDAY INSPECTION OF 3‐LAYER PE COATED PIPES
Prior to placement of the steel reinforcement and/or application of concrete coating, the entire factory applied anticorrosion coating of the pipe shall be visually inspected.
Any foreign matter shall be removed from the surface of the anticorrosion coating and each detected coating damage shall be repaired according to the approved procedure prior to the commencement of the concrete coating application.
Then, the entire coated surface of the pipes shall be inspected using a holiday detector at a voltage of minimum 25 kV. The holiday detector shall be equipped with a visual and an acoustic signalling device clearly audible in the prevailing working conditions. All damages detected by the holiday detector shall be repaired.
6.2 PLACEMENT OF REINFORCEMENT STEEL
For concrete thickness up to 50 mm, one wrap of reinforcing shall be used. For thicknesses of more than 50 mm, two layers should be considered. Additional layers may be necessary for concrete thicknesses in excess of 120 mm, but this would then require further COMPANY/CONTRACTOR’s approval, so the number of steel reinforcing layers shall be as follows:
concrete coating thickness up to 50 mm 1 layer;
concrete coating thickness from 51 mm up to 100 mm 2 layers; concrete coating thickness from 101 mm up to 140 mm 3 layers.
According to SUBCONTRACTOR’s discretion, SUBCONTRACTOR may apply also the combination of the reinforcing steel cage and reinforcing steel welded wire mesh but the above mentioned number of reinforcing layers vs. concrete coating thickness and the requirements for percentage of reinforcing steel in concrete coating cross sectional areas must be respected. During the application of the reinforcing steel, at all times, the following requirements must be met: minimum 15 mm distance between the reinforcing steel and the factory applied anticorrosion pipe coating; minimum 10 mm distance between the reinforcing steel and the outer surface of applied concrete coating; minimum 10 mm distance between two layers of reinforcing steel. In case the reinforcing steel welded wire mesh is used, the longitudinal overlap of the wire mesh shall be minimum 25 mm. In case the cage type of reinforcement is used, the steel reinforcement shall terminate: 10 mm – 30 mm from the end of concrete coating.
7
APPLICATION OF COATING MATERIALS
It will be the SUBCONTRACTOR’s decision to apply the concrete coating using impingement method or compression coat method (extrusion), however only the application method used during the successfully passed and completed pre‐qualification test shall be used.
Prior to the application of the concrete coating, the temperature of the concrete coating mix shall be within the range between +5°C and +35°C.
In case the temperature of the concrete coating mix is less than +5°C, the concrete coating shall not be performed until SUBCONTRACTOR manages to heat the entire concrete mix up to +5°C. In case the temperature of the concrete coating mix is higher than +35°C, the mixing water shall be cooled with ice or a suitable cooling system shall be provided for the mixing water in order to obtain the concrete mix temperature of maximum +35°C. The free water/cement ration shall not exceed 0.45 by weight. The concrete coating application method shall be such that the coating time for each pipe does not exceed 30 minutes (starting from the moment that the water was added to the concrete mix and the concrete coating application started on that particular pipe up to the completion of application of concrete coating on the same pipe) otherwise the concrete coating on that pipe shall be rejected.
Use of reclaimed/rebound material might be allowed providing it is demonstrated that it does not have any detrimental effect on the final concrete product.
Secondary mixing of the reclaimed material with freshly batched concrete must follow immediately and must produce a homogeneous cohesive mixture. The amount of recycled material used shall not exceed 10% of the total mix by weight. If a break of this operation, for whatever reason, exceeds 30 minutes any reclaimed material not previously added to the mix shall be discarded and removed from the coating area. 7.1 PREPARATION OF THE CUTBACK AREA The concrete coating shall be removed at both pipe ends taking care not to damage pipe steel or factory applied anticorrosion coating. The length of such prepared concrete coating cutback shall be 380 mm (‐ 0 mm / + 20 mm). The cutback shall be square with respect to pipe axis. 7.2 FINISHING OPERATIONS WITHIN CONCRETE COATING PLANT
Surface fallouts (spalling) shall be filled by guniting. The repair mix shall be similar in composition to the original mix. The repair shall be carried out in accordance with approved procedure within 30 minutes after application of the original concrete coating mix.
Surface damage on concrete coating shall not be considered as a defect if all of the following conditions have been met:
damage is not extended to more than 20% of the nominal concrete coating thickness; damaged area is less than 1000 cm2 (0.1 m2).
In case the total area of fall‐outs (spalling) is more than 20% of the concrete surface, the concrete coating shall be removed from that particular pipe.
The cutback area and internal pipe surface shall be completely free from any residual concrete coating material and from any materials detrimental to the welding, NDT and field joint coating operations which shall be performed by pipe laying CONTRACTOR during the pipe laying operations. Finally, each pipe end shall be protected with end cap and the exposed steel and the first 100 mm of 3‐ layer PE coating shall be wrapped with polyethylene sheet that does not contain any adhesive and which shall be firmly tightened around this pipe location. 7.3 CURING Immediately after completion of the application of concrete coating operations, the concrete coated pipe passing all online inspections and tests shall be transferred to the curing area. During the curing period, the pipes shall be stacked in a single layer. Curing shall be performed either by using water curing, steam curing, curing by sealing compounds or by polyethylene wrapping. The exposed surfaces of the concrete coating shall be protected during the curing period from any adverse effects of sunshine, drying winds, rain or running water.
The curing process shall continue until a minimum compressive strength of 14 MPa has been achieved when the compression strength test is performed on core samples after which the concrete coated pipe can be lifted, transported and stacked in more than one layer up to the maximum allowed number of stacking layers. In case the period when the pipe reaches minimum 14 MPa of compression strength on core samples has not been determined by practical tests, the pipes shall remain stacked in a single layer for minimum seven days.
Locations where the core samples shall be taken from the pipe for this purpose shall be selected by COMPANY/CONTRACTOR.
7.3.1 WATER CURING
Water curing shall consist of wetting and moistening the concrete coating, starting not later than 6 hours after completion of concrete coating application.
The concrete coating shall be kept continuously moist by intermittent spraying for a period of at least 7 days. The interval between spraying shall not be more than 24 hours. At the ambient temperatures below +4°C, suitable precautions shall be taken to prevent damage due to freezing.
7.3.2 STEAM CURING
If the curing process involves steam or warm high‐humidity air, then it shall be demonstrated that the process will have no deleterious effects on the concrete. Under no circumstances shall the pipe wall be allowed to reach a temperature that would cause any damage to the anticorrosion coating.
Curing by steam shall not start sooner than 3 hours after completion of the concrete coating application completion.
Concrete coated pipes shall be enclosed in plastic or similar cover suitable to maintain steam circulation. Steam circulation shall start at the ambient temperature and shall be controlled to give a temperature gradient of approximately 10°C/hour up to the maximum steel or coating temperature of +60°C.
The pipes shall be held under steam curing for at least 6 hours and then allowed to cool for a similar period. SUBCONTRACTOR shall demonstrate during the pre‐qualification test that the curing time used is sufficient to meet the specified concrete strength levels.
7.3.3 CURING BY SEALING COMPOUNDS
Sealing compounds shall meet requirements of ASTM C 309 – 98A standard. The material shall be stored, prepared and applied in accordance with instructions supplied by the MANUFACTURER of sealing compounds.
The compound shall be non‐toxic and non‐flammable and shall not react with any constituent of the concrete, reinforcement, protective coating or pipe steel.
Unless otherwise specified by the compound MANUFACTURER’s instructions, membrane sealing compounds shall be sprayed over the complete concrete surface within 6 hours after completion of the concrete application and shall remain for a minimum of 7 days. The materials shall not be applied at temperatures less than +4°C.
7.3.4 CURING UNDER POLYETHYLENE WRAPPING
Wrapping in polyethylene film shall be done during the application of concrete coating. A light spray of water shall be applied before applying the plastic film. The polyethylene film shall have a minimum thickness of 0.2 mm and the overlap of the sheet shall not be less than 25% of the sheet width. The polyethylene film shall be in accordance with ASTM C 171 standard. The interface between the concrete and the bare steel at the pipe ends shall also be protected in order to achieve an air‐tight seal. The polyethylene wrapping shall remain on the pipe for minimum seven days but it shall be removed prior to final load out of the pipe.
7.3.5 FOG CURING
Fresh concrete coating is continuously moistened by mist released from fogging tips and covered with tarpaulin sheets to provide a “closed” environment for curing.
“Atomized” mist, with high “wet‐ability” is introduced gradually building to a “closed” high humidity, near saturation ambience to facilitate proper curing environment. The continuous introduction of “atomized” fog/mist into tarpaulin shall be continued for one shift before the pipe is removed/subject to further handling.
8
INSPECTION AND TESTING
The Pre‐Qualification Test shall be performed on five fully concrete coated pipes and shall be completed before the start of actual production in the PROJECT. The combination of pipe material vs. pipe external diameter vs. pipe wall thickness vs. concrete coating thickness selected for Pre‐Qualification Test shall be agreed between SUBCONTRACTOR and COMPANY/CONTRACTOR. It is mandatory that all five concrete coated pipes are concrete coated in a sequence without any stoppage of the concrete coating plant in order to allow performance of the off‐line PQT tests. In case this requirement is not met, the PQT shall be repeated.All of the inspections and tests listed in this document shall be addressed in the inspection and test plan. Defects or anomalies detected during coating process shall start immediate corrective actions from the SUBCONTRACTOR.
All line pipes to be submitted to the inspections and tests shall be selected in agreement with the COMPANY/CONTRACTOR’s Inspector.
In the event that a production line pipe fails to meet the acceptance criteria for the tests listed in the table the test can be repeated only should the failure be caused either by improper use of the testing equipment or by error in the testing procedure.
The following inspections and tests shall be carried out:
Inspection/Test Reference PQT Production
Inspection of the 3‐layer PE coated pipes during the receipt Section 6 Section 8.2 Before the start of the PQT. Before the start of production. Visual inspection of the stacking of the 3‐layer
PE coated pipes
Section 8.1 Before the start of the PQT. Periodically. Inspections of the concrete coating materials
during their receipt Section 8.3 Section 8.4.1 Section 8.4.2 Section 8.4.3 Before the start of the PQT. Mixing water certificate to be delivered before the start of the PQT.
Each package of received concrete coating material.
Verification of calibration of the holiday detector and the concrete coated pipes weighing scale
Section 8.5 Section 8.5.1 Section 8.5.2
Before the start of the PQT. Once per day.
Visual and holiday inspection of 3‐layer PE coated pipes immediately before application of concrete coating
Section 8.6
Each PQT pipe. Each pipe.
Concrete coating mix control (verification of calibration of the concrete coating mixing plant)
Section 8.7 Before the start of the PQT. Once per week.
Concrete coating mix temperature check Section 8.8 Once. When the ambient temperature is within the range from +10°C up to +25°C, the test shall not be carried out.
In case the ambient temperature is outside the above mentioned range the concrete coating mix
temperature shall be measured at the beginning of each working shift and then every 4 hours.
Water – cement ratio check Section 8.9 Once. First working shift of each working day.
Inspection/Test Reference PQT Production
Verification of the correct positioning of the concrete coating steel reinforcement
Section 8.10 First two PQT pipes. One pipe concrete coated at the beginning and on one pipe concrete coated in the middle of each working shift.
Concrete coating application control Section 8.11 Each PQT pipe. Each pipe. Measurement of external diameter of applied
concrete coating
Section 8.12 Each PQT pipe. Each pipe. Cutback control Section 8.13 Each PQT pipe. Each pipe. Weighing of freshly concrete coated pipe Section 8.14 Each PQT pipe. Each pipe. Calculation of negative buoyancy Section 8.15 Each PQT pipe. Each pipe. Visual inspection of applied concrete Section 8.16 Each PQT pipe. Each pipe. Measurement of the electrical resistance
between the steel reinforcement and the pipe
Section 8.17 Reinforcing steel wire mesh: each PQT pipe.
Steel cage:
On the pipes where the test for verification of the correct positioning of the concrete coating steel reinforcement has been performed.
Reinforcing steel wire mesh: each PQT pipe. Steel cage:
On the pipes where the test for verification of the correct positioning of the concrete coating steel reinforcement has been performed.
Control of the curing process and control of stacking of concrete coated pipes during the curing process
Section 8.18 Section 8.19
Each PQT pipe. Periodically.
Control of marking on concrete coated pipes Section 8.20 Each PQT pipe. Each pipe. Control of the concrete coating repair Section 8.20 Each PQT pipe. Each pipe.
Control of the concrete coating repair Section 8.21 Each PQT pipe. Each pipe on which the concrete coating has been repaired.
Determination of factor α in the formula for calculation of negative buoyancy (performance of this test is not mandatory)
Section 8.22 Two PQT pipes not submitted to the water absorption test.
N/A.
Compression strength test cubes Section 8.23 Each PQT pipe. 4 cubes from first pipe at the beginning of each working shift and then every 25 pipes. Compression strength test on core samples Section 8.24 Each PQT pipe. 2 x 3 cores from first pipe at the beginning of
each working shift and then every 15 pipes. Determination of the time for stacking of pipes in more than one layer (performance of this test is not mandatory) Section 8.25 Three PQT pipes. N/A.
Water absorption test Section 8.26 Two PQT pipes. One pipe coated each day during the first three production days.
In case all tests had acceptable results the test shall be performed once per shift. week Adhesion between the 3‐layer PE coating and
concrete coating
Section 8.27 One test. N/A.
Impact testing Section 8.28 When Requested When Requested one per week Stacking of cured CWC pipes Section 8.29 N/A Each pipe.
Load out inspections Section 8.30 N/A Each pipe.
8.1 STACKING OF 3‐LAYER PE COATED PIPES
Periodical visual inspection shall be performed in the area dedicated for stacking of the pipes coated with 3‐layer PE awaiting the application of concrete coating in order to verify that these pipes have been stacked in a maximum allowed number of layers and that they have been stacked on approved supports. In case of non‐conformance with relevant requirements SUBCONTRACTOR shall inform COMPANY/CONTRACTOR who will bring further decisions and COMPANY/CONTRACTOR’s decision shall be binding.
8.2 CONTROL, IDENTIFICATION AND SEGREGATION OF 3‐LAYER PE COATED PIPES
The 3‐layer PE coated pipes shall be visually inspected for bevel damages, dents, gauges, flat ends and coating damages. Also the content of agreed pipe marking required at this stage of work shall be verified on the pipe.
In case bevel damages, significant corrosion, dents, gouges, lamination or flat ends have been detected on bare pipe portion at the cutback area, the pipe shall be marked with coloured tape, segregated if practical to do so, and brought to COMPANY/CONTRACTOR’s attention who will instruct SUBCONTRACTOR about actions to be taken on this pipe.
In case the coating damage has been detected, damaged area shall be marked and coloured tape shall be put around that pipe which shall remain on the pipe until the coating repair has been completed and approved by COMPANY/CONTRACTOR.
In case oil, grease or any similar contamination has been detected at the cutback area, the contamination shall be removed with fresh water and detergent, solvent or any other suitable method.
In case the missing or incorrect pipe marking has been detected, the pipe shall be marked with coloured tape, segregated if practical to do so and brought to the COMPANY/CONTRACTOR’s attention who will instruct SUBCONTRACTOR about the actions to be taken on that pipe.
8.3 DELIVERY AND STORAGE OF CONCRETE COATING RAW MATERIALS
At each delivery of the coating raw materials, the received documentation shall be reviewed against the received material packages and against the Purchase Order documents in order to verify that the received documents and materials conform to the requirements specified in the purchase order.
In case of any non‐conformance, it shall be the SUBCONTRACTOR’s responsibility to resolve this issue with the supplier of the non‐conforming material. However, the batch of the material delivered in SUBCONTRACTOR’s premises non‐conforming to the requirements of this specification, shall not be used in the PROJECT.
Periodically, a visual inspection shall be performed in order to verify that the coating materials have been stored in conditions as recommended by the material MANUFACTURER.
The cement shall be stored in proper waterproof silos.
The aggregates can be stacked in stockpiles at the open on clean site, free from the possibility of contamination. The galvanized wire mesh may be stored at the open clean site free from possibility of contamination but the wires used for manufacturing of steel cage must be stored in closed storage facility in dry place. The polyethylene wrapping that shall be used for curing of concrete coated pipes may be stored outside in clean site but it must be covered with appropriate sheeting to avoid exposure to the rain and raised from the ground to avoid flooding.
COMPANY/CONTRACTOR reserves the right to reject the use of improperly stored material in the PROJECT. 8.4 TEST TO BE PERFORMED ON CONCRETE COATING MATERIAL UPON RECEIPT 8.4.1 SIEVE ANALYSIS AND CLEANLINESS CONTROL OF AGGREGATES The grading and cleanliness of aggregates shall be checked from each stockpile for cleanliness and grading. The grading shall be as per the nominal values and tolerances specified by SUBCONTRACTOR and verified during the PQT. The test for cleanliness shall mean visual inspection for presence of any foreign material in tested sample beside the tested aggregate itself (wood, shells, or any other similar contaminant).
In case of test failure, the test shall be repeated on doubled number of samples taken from the same batch. In case of repeated failure, the affected batch of supplied material shall not be used in the PROJECT or it shall be cleaned from all contamination as per COMPANY/CONTRACTOR’s satisfaction. Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, tested material, material supplier, material batch number if applicable, acceptance criteria, test results, remarks. 8.4.2 STEEL REINFORCEMENT WIRES DIMENSIONAL CONTROL For each batch of received reinforcing steel some of the received rolls of wire mesh and/or the wires for cage type reinforcement shall be checked by measuring the diameter of longitudinal and stay wires with a calliper.
The measured value shall correspond to the minimum value provided by the reinforcing steel MANUFACTURER required to meet the requirements for reinforcing steel in concrete coating in this specification (minimum tolerance specified first by relevant standard and if this value cannot be found in the standard then the minimum tolerance value can be specified by the MANUFACTURER).
In case of test failure, the test shall be repeated on doubled number of samples taken from the same batch. In case of repeated failure, the affected batch of supplied material shall not be used in the PROJECT. Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, tested material, material supplier, material batch number if applicable, acceptance criteria, test results, remarks. 8.4.3 MIXING WATER CHEMICAL ANALYSIS Water used in concrete coating mix shall be fresh and shall comply with Appendix A of BS EN 1008. During the bidding stage of the PROJECT the SUBCONTRACTOR shall present the certificate for the mixing water used in the coating plant and the SUBCONTRACTOR shall provide the written guaranty that the same water shall be used during entire SUBCONTRACTOR’s work in the PROJECT.
In case the above mentioned requirement is not met, the chemical analysis of mixing water shall be completed and the certificate submitted to COMPANY/CONTRACTOR two weeks before the commencement of the Pre‐Qualification Test otherwise SUBCONTRACTOR shall not be allowed to start the performance of the pre‐qualification test. In case the quality of mixing water does not meet the requirements of this specification, the concrete coating plant shall not be qualified for the work.
8.5 VERIFICATION OF CALIBRATION OF THE TEST INSTRUMENTS
The verification of calibration shall be verified for the holiday detector and pipe weighing scales each working day while the calibration of other testing equipment shall not be verified but the Third Party’s calibration certificates shall be used.
The instruments whose accuracy is not meeting the relevant acceptance criteria for each particular instrument shall not be used in the PROJECT until the instrument’s accuracy is brought back within acceptable limits.
Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, testing equipment, testing equipment serial number, acceptance criteria, test results, remarks.
8.5.1 HOLIDAY DETECTOR
The voltage of the holiday detector shall be compared with the voltage of the certified calibration high voltage instrument recommended by the MANUFACTURER of the holiday inspection equipment for this purpose. The holiday detector shall be considered acceptable when the voltage of the holiday detector when checked with the high voltage calibration instrument set at 25.0 kV shows the values within the range from 25.0 kV to 25.5 kV. 8.5.2 PIPE WEIGHING SCALES The verification of calibration of the weighing scales which shall be used for determination of the weight of freshly concrete coated pipes shall be performed by weighing of the minimum 11.5 m long minimum 10” diameter pipe having known and certified weight. The weighing bridge shall be considered acceptable for use when the measured value of the known weight is within the range: Nominal weight of the pipe having known and certified weight ± 0.3%.shift. 8.6 VISUAL AND HOLIDAY INSPECTION OF THE 3‐LAYER PE COATED PIPES
Prior to the commencement of application of the concrete coating, the 3‐layer PE coated pipes shall be submitted to the visual inspection and holiday inspection at 25 kV.
The pipes shall have no major steel defects and the pipe coating shall be without visible defects. There shall be no holidays detected after holiday inspection at 25 kV.
The 3‐layer PE coating shall be repaired in accordance with the SUBCONTRACTOR’s coating repair procedure approved by COMPANY/CONTRACTOR.
Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity only in case any not conformance occurred.
8.7 CONCRETE COATING MIX CONTROL
Prior to the commencement of the pre‐qualification test and during the production once per week, SUBCONTRACTOR shall perform the verification that their batching plant provides the composition of the concrete coating mix within the tolerances selected by the SUBCONTRACTOR himself. Production shall not start if the batching plant is not properly calibrated.
Within the concrete coating application procedure, SUBCONTRACTOR shall describe in details the verification of calibration of batching plant for determination of percentage of each component in the concrete coating mix.
8.8 CONCRETE COATING MIX TEMPERATURE MEASUREMENT
When the ambient air temperature is less than +10°C and it is higher than +25°C, SUBCONTRACTOR shall measure the temperature of the concrete coating mix at the beginning of each working shift and then every 4 hours.
Approximately 3 ‐ 10 kg of concrete mix shall be taken at the end of the belt located after exit of the mixer and put into the bucket or any other suitable container.
Then, the immersion probe of the digital thermometer shall be immersed in the fresh concrete mix and the temperature shall be read from the display of the instrument.
In case the temperature of the concrete coating mix is less than +5°C, the concrete coating shall not be performed until SUBCONTRACTOR manage to heat the entire concrete mix up to +5°C. In case the temperature of the concrete coating mix is higher than +35°C, the mixing water shall be cooled with ice or a suitable cooling system shall be provided for the mixing water in order to obtain the concrete mix temperature of maximum +35°C. Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, acceptance criteria, test results, remarks. 8.9 WATER‐CEMENT RATIO CHECK The free water / cement ratio shall be checked at the beginning of the first working shift of each working day. The water to cement ratio shall not exceed 0.45 by weight.
In case the acceptance criterion is not met, the concrete coating operations shall not start it has been verified that the water/cement ratio is within acceptable limits.
Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, acceptance criteria, test results, remarks. 8.10 REINFORCING WIRE POSITION CONTROL
On one pipe concrete coated at the beginning and on one pipe concrete coated in the middle of each working shift, the proper positioning of the reinforcing steel wire mesh shall be verified by opening a window of approximate dimensions 200 mm x 75 mm penetrating down to the anticorrosion pipe coating while the concrete coating is still fresh.
During this visual inspection it shall be verified that the requirements specified in Section 8.2 of this specification have been met.
Only in case the cage type steel reinforcement is used by SUBCONTRACTOR, during this test it shall be tested also the electrical resistance between the bottom layer of the reinforcing steel and the pipe end. One electrode of the ohmmeter shall be in the contact with the bottom layer of the reinforcing steel of the cage and another electrode shall be in the contact with bare pipe end at the cutback area. The minimum measured resistance shall be 1 000 Ohm.
In case the acceptance criteria have not been met, the testing shall continue until it is determined on two consecutive pipes concrete coated before and on two consecutive pipes concrete coated after the test failure, that these tests are successfully passed. The pipes not passing any single of these tests shall have the concrete coating removed. 8.11 CONCRETE COATING APPLICATION CONTROL During the application of the concrete coating the following verifications shall be carried out on each pipe: that the concrete has been applied reasonably uniformly throughout the entire pipe length and that it has been applied without any major irregularities; that the spalling is repaired on the freshly concrete coating pipe maximum 30 minutes after adding the water in the concrete coating mix in the concrete batching plant; when the reinforcing steel in the form of wire mesh is used that the polyethylene wrapping has been applied immediately after the concrete application with minimum overlap of 25 % of the sheet width.
Pipes not meeting acceptance criteria shall have the concrete coating removed. 8.12 MEASUREMENT OF EXTERNAL DIAMETER OF APPLIED CONCRETE
The external circumference/diameter of applied concrete shall be measured on each concrete coated pipe using a flexible measuring tape at five equidistant points along the pipe length.
The measurements shall not be taken at first 400 mm from the ends of applied concrete coating. The average of five measurements for external diameter of applied coating shall than be inserted in the formula for calculation of negative buoyancy.
Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, pipe sequence number, pipe number, pipe external diameter, pipe wall thickness, pipe nominal concrete coating thickness, test results, remarks.
8.13 CUTBACK CONTROL
The cutback length shall be measured on each concrete coated pipe end. The average of two measurements shall be inserted in the formula for calculation of negative buoyancy.
The edges of concrete coating at the cutback area shall be perpendicular with respect to the pipe axis and entire concrete coating cutback area shall be free of residual concrete coating and from any materials detrimental to the welding, NDT and field joint coating operations which shall be performed by the pipe laying CONTRACTOR during the pipe laying operations.
The concrete coating cutback length shall be 380 (‐ 0 mm / +20 mm).
In case the acceptance criteria have not been met, the pipe shall be quarantined until the remedial work is taken which shall result in acceptable concrete coating cutback.
Relevant inspection report specifying cutback lengths shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, pipe sequence number, pipe number, pipe external diameter, pipe wall thickness, pipe nominal concrete coating thickness, acceptance criteria, result of each cutback length measurement, remarks. 8.14 WEIGHING OF FRESHLY CONCRETE COATED PIPE Each freshly concrete coated pipe shall be placed on a weighing scale where its weight shall be measured. The result shall be displayed and when the pipe weight has stabilized. The result of measurement shall be inserted in the formula for calculation of negative buoyancy. Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, pipe sequence number, pipe number, pipe external diameter, pipe wall thickness, pipe nominal concrete coating thickness, test results, remarks. 8.15 CALCULATION OF NEGATIVE BUOYANCY The negative buoyancy shall be calculated on each pipe as follows: NB = negative buoyancy [kg/m]; Wbp = weight of bare pipe, information supplied from the pipe MANUFACTURER [kg];
W3LPE/3LPP = weight of applied 3‐layer PE/3‐layer PP not including mass of bare pipe, calculated using either nominal or average 3‐layer PE or other external anticorrosion coating thickness [kg];
L = length of the line pipe taken the data from pipe MANUFACTURER [m]; CB3LPE/3LPP = average of two measurements of the 3‐layer HDPE/3‐layer PP cutback length;
theoretical average is also allowed for this purpose [m];
CBCWC = average of two actually taken measurements of the concrete coating cutback length on which the length has been measured [m];
α = factor of change in the weight of concrete coating from wet and fresh to dry and cured; unless otherwise demonstrated during the PQT, the factor α = 0.99 [non dimensional value];
WCWC = weight of the pipe coated with fresh concrete, measurement taken immediately after application of concrete coating [kg];
DCWC = external diameter of the concrete coated pipe obtained by average of five measurements of the concrete coating circumference as per this specification divided by π [m]; ρW = density of seawater. The acceptance criteria for negative buoyancy for each combination of pipe external diameter vs. pipe wall thickness vs. concrete coating thickness shall be provided by COMPANY/CONTRACTOR in due time. Only unless otherwise communicated by COMPANY/CONTRACTOR the following tolerances shall apply: per working shift: nominal value of negative buoyancy (‐0% / +4.5%); per single concrete coated pipe: nominal value of negative buoyancy (‐0% / +10%). Each pipe not meeting acceptance criteria have the concrete coating removed. Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity. The report shall contain the following items: date, shift, pipe sequence number, pipe number, pipe external diameter, pipe wall thickness, pipe nominal concrete coating thickness, acceptance criteria, test results, remarks. 8.16 VISUAL INSPECTION OF APPLIED CONCRETE Each freshly concrete coated pipe shall be visually inspected for defects. Surface damage on concrete coating shall not be considered as a defect if all of the following conditions have been met: damage is not exposing reinforcing steel; damage is not extended to more than 20% of the nominal concrete coating thickness; damaged area is less than 1000 cm2 (0.1 m2). Relevant inspection report shall be prepared by SUBCONTRACTOR related to this inspection activity.
The report shall contain the following items: date, shift, pipe sequence number, pipe number, pipe external diameter, pipe wall thickness, pipe nominal concrete coating thickness, test results, remarks. The following shall be considered during visual inspection of concrete coated pipes. 8.16.1 SURFACE FALL‐OUTS (SPALLING) OF FRESHLY CONCRETE COATED PIPES In case the spalling occurs, it shall be repaired only if the maximum 20% of the concrete coating surface is affected by it. The spalling shall be repaired in production line within 30 minutes after application of the original concrete coating mix or in case this time is exceeded by guniting using the concrete composition similar to the original concrete coating mix applied on the pipe. After repair the pipe shall be reweighed for calculation of negative buoyancy. 8.16.2 CONCRETE COATING DAMAGES ON FRESH AND HARDENED CONCRETE
Damages caused by taking of core samples for compression strength test shall be repaired unless the anticorrosion pipe coating has been damaged. In case the anticorrosion coating has been damaged during the core sampling process, the concrete coating shall be removed from that pipe.
In case reinforcing steel has been only cut but not removed from the pipe, the concrete coating can be repaired and the reinforcing steel shall be positioned properly during the repair.
However, if any portion of reinforcing steel has been removed from the pipe, the concrete coating shall be removed from that pipe.
Concrete coating damages resulting also in damage of the 3‐layer PE coating shall have the concrete coating removed.
Considering above mentioned limitations, repair of concrete coating damages is allowed when the concrete coating has been damaged or it has been removed from the pipe for repair purposes up to maximum 20% of the concrete coating surface (not of the concrete coating volume.
8.16.3 CRACKS
Circumferential surface cracking of the concrete not exposing reinforcing steel having a crack width less than 5 mm shall not be considered as a defect.
Circumferential annular cracking visible at pipe ends is generally not acceptable and all pipes having such cracks in total circumferential length greater than 200 mm shall have the concrete coating removed. All cracks penetrating down to the 3‐layer PE coating shall not be acceptable and such pipe shall have the concrete coating removed.
Longitudinal surface cracks less than 250 mm in length and having a width of 8 mm or less shall not be considered as a defect but holes of 10 mm nominal diameter shall be drilled at the crack tips to prevent propagation of the crack. The bottom of these holes shall be 7‐10 mm from the anticorrosion coating. Longitudinal cracks having a length from 250 mm up to 1000 mm shall be repaired by chiselling out the crack to a width of at least 25 mm throughout its length taking care not to damage anticorrosion coating.
