NACE MR0175/ISO 15156-3
GENERAL REMARKS:
A.2.2 including Table A.2 QUESTION:
A.2.2 including Table A.2 QUESTION:
Paragraphs 4.2 and 4.2.1 refer to all CRAs being used in contact with well fluids but do not necessarily include instrument or control tubing (Bourdon tubes) being used in pressure indicators as listed in Paragraph 8.4.4.1. Currently this means that 316 stainless steel alloys (L, Ti, etc.) containing those elements are not ruled out from their being used in gauges where the well fluid wetted parts are not exposed to fluids that do not exceed:
4.2.2 The maximum acceptable H2S partial pressure shall be 100 kPa abs (15 psia) at a maximum temperature of 60°C (140°F), with no restrictions on chlorides, and no elemental sulfur.
If the chloride content is less than 50 mg/L, the H2S partial pressure shall be less than 150 kPa abs (50 psia).
Each application is subject to the specific environmental conditions to the equipment supplier, particularly if the equipment will be used in sour service.
Under the above stated conditions, do gauges that are made with 316 SS alloy steels comply with NACE Standard MR0175-2003?
(MP INQUIRY #2003-18) REVISED ANSWER 2005-09-01:
You have correctly cited Paragraph 4.2 of MR0175 for the general use of austenitic stainless steels. It is the manufacturer's responsibility to determine whether the 316 SS meets the metallurgical requirements of this paragraph, including the requirement that the alloy will be "free of cold work . . . "
--There is no exclusion for Type 316 stainless steel from the metallurgical or the environmental requirements of Paragraph 4.2 in Paragraph 8.4.2 of MR0175-2003.
--NACE will adopt in 2003 the ISO 15156 document as being technically equivalent to MR0175. At this time there will be only a joint standard, NACE MR0175/ISO 15156. The NACE MR0175 2003 edition will cease to exist.
See revised version of Table A.2 included in Reference 3.
A.2.2, Table A.3 QUESTION:
Paragraph 4.3.1 for UNS S20910 allows this material to be used in sulfur-free environments when the maximum H2S partial pressure is 15 psia to 150°F in the annealed or hot-rolled (hot/cold-worked) condition at 35 HRC maximum hardness.
Paragraph 9.4.1 for UNS S20910 allows this material to be used for valve shafts, stems, and pins at a maximum hardness level of 35 HRC in the cold-worked condition, provided this cold working is preceded by a solution-anneal heat treatment.
Does this mean that I can use UNS S20910 for valve stems in the cold-worked condition (preceded by a solution-anneal heat treatment) at 35 HRC max with no environmental restrictions?
(MP INQUIRY #2003-12 Q3) ANSWER:
There are no environmental restrictions for UNS S20910 permitted at the higher hardness of 35 HRC in Paragraph 9.4.1 for the applications defined in Paragraph 9.4. Please see the attached Table A.3 from ISO 15156, which provides the correct interpretation of this paragraph. NACE will be adopting ISO 15156 in 2003 as a technically equivalent document.
A.2.2, Table A.2, Table A.3, and Table A.6
Note: The revised version of Table A.2 is included in Reference 3.
QUESTION:
SUBJECT: Paragraph 9.4 of NACE MR0175-2003 Standard
QUESTION: Are shafts, stems, and pins used in valves, unloaders, and other devices, when manufactured from austenitic stainless steel materials in accordance with Section 4 of NACE MR0175-2003, acceptable for use in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature and free elemental sulfur?
QUESTION: If the answer to the former question is no, what are the specific environmental limits?
(MP INQUIRY #2003-36) ANSWER:
1) For stainless steels, the environmental limits of Paragraph 4.2 apply (as opposed to compressors where in Paragraph 11.4.7 there are no restrictions).
(2) For individual alloy UNS S20910 there are no environmental restrictions if cold work and hardness are set within the restrictions of Paragraph 9.4.1 in Table A.3 of NACE MR0175/ISO 15156-3. Since in Paragraph 9.4.1 of MR0175-2003 there are no environmental restrictions, then the environmental restrictions of Paragraph 4.3.1 do not apply for shafts, stems, and pins.
QUESTION:
SUBJECT: Paragraph 9.4 of NACE MR0175-2003 Standard
QUESTION: Are shafts, stems, and pins manufactured from austenitic stainless steels in accordance with and meet the hardness and heat-treat requirements of Section 4 of MR0175-2003 acceptable for use in sour environments with no
environmental limits with respect to chloride content, partial pressure of H2S, temperature and free elemental sulfur?
QUESTION: Is the answer to the above question in agreement with ISO 15156?
(MP INQUIRY #2003-37) ANSWER:
(1) For stainless steels, the environmental limits of Paragraph 4.2 apply (as opposed to compressors where in Paragraph 11.4.7 there are no restrictions).
(2) For individual alloy UNS S20910 there are no environmental restrictions if cold work and hardness are set within the restrictions of Paragraph 9.4.1 in Table A.3 of ISO 15156-3. Since in Paragraph 9.4.1 of MR0175-2003 there are no environmental restrictions, then the environmental restrictions of Paragraph 4.3.1 do not apply for shafts, stems, and pins.
A.2.2, Table A.2 and Table A.6
Note: The revised version of Table A.2 is included in Reference 3.
QUESTION:
SUBJECT: Paragraph 9.3 of NACE MR0175-2003 Standard
The packaging content of large skid-mounted gas compressors applied in the oil and gas, gas processing, and process industries generally include several valves varied in type, such as relief valves, ball valves, globe valves, plug valves, gate valves, butterfly valves, and check valves installed on scrubbers, in process gas piping, and in off-skid mounted header systems and sometimes contain chokes in higher pressure scrubber drain systems. Are the body and bonnet components of valves, when manufactured from austenitic stainless steel materials in accordance with Section 4 of NACE MR0175-2003, acceptable for use in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur.
(MP INQUIRY #2003-35 Q1) ANSWER:
The latest editions of API Standard 618 for Reciprocating compressors and API Standard 617 for Axial and Centrifugal compressors define the scope of equipment associated with the compressor environment including accessories, instrumentation and piping systems. It is the user’s responsibility to determine whether the equipment mentioned in your inquiry is directly associated with the compressor and experiences the same service environment as inferred for compressors in NACE MR0175/ISO 15156-2003 Table A.6.
QUESTION: If the answer to the former question is no, what are the specific environmental limits?
(MP INQUIRY #2003-35 Q2) REVISED ANSWER 2005-09-01:
a) The austenitic stainless steels when used outside the compressor
environment are subject to the environmental restrictions in NACE MR0175/ISO 15156-2003 Table A.2.
See revised version of Table A.2 included in Reference 3
b) The austenitic stainless steels were restricted because of industry and lab failures.
QUESTION: Are the non-pressure-containing components of valves, when manufactured from austenitic stainless steel materials in accordance with Section 4 of NACE MR0175-2003, acceptable for use in sour environments with no environmental limits with respect to chloride content, partial pressure of H2S, temperature, and free elemental sulfur?
(MP INQUIRY #2003-35 Q3) ANSWER:
a.) The user must determine if individual components or parts of equipment must meet the requirements of NACE MR0175/ISO 15156-2003.
b) NACE MR0175-2003 provided guidance for this applicability of the standard in Paragraph 1.3. This paragraph stated that “This standard applies to all components where failure by SSC or SCC would (1) prevent the equipment from being restored to an operating condition while continuing to contain pressure, (2) compromise the integrity of the system, and/or (3) prevent the basic function of the equipment from occurring.” These guidelines can be applied within NACE MR0175/ ISO 15156-2003.
QUESTION: If the answer to the former question is no, what are the specific environmental limits?
(MP INQUIRY #2003-35 Q4) ANSWER:
The austenitic stainless steels when used outside of the compressor environment are subject to the environmental restrictions in NACE MR0175/ISO 15156-2003 Table A.2.
Note: The revised version of Table A.2 is included in Reference 3.
QUESTION: Are the answers to all of the above questions in agreement with ISO 15156?
(MP INQUIRY #2003-35 Q5) ANSWER:
Yes.
QUESTIONS:
I have an application where I am supplying a pipeline from a gas compressor to a turbine generator. The pipe is 10 in. in diameter and contains natural gas with H2S.
The H2S concentration is 250 ppm by volume. The gas is pressurized to 475 psi
@152°F. I would like to know what table from Annex A this pipe would fall under.
The material I would like to use is 304L SS, which satisfies the requirements in A.2.
I would appreciate any guidance you can provide with this subject.
(MP INQUIRY #2004-02) ANSWERS:
1a) NACE MR0175/ISO 15156-3:2003 Table A.6 provides environmental and materials limits for austenitic stainless steels used in compressors. NACE
MR0175/ISO 15156-3:2003 Table A.2 applies to austenitic stainless steels used for any equipment or components.
Note: The revised version of Table A.2 is included in Reference 3.
b) The limits on austenitic stainless steels in NACE MR0175/ISO 15156-3:2003 Table A.6 (when compared to those of NACE MR0175/ISO 15156-3:2003 Table A.2) are based upon industry experience with these alloys in compressors.
c) The latest editions of API Standard 618 for Reciprocating compressors and API Standard 617 for Axial and Centrifugal compressors define the scope of equipment associated with the compressor environment including accessories, instrumentation, and piping systems.
d) It is the user’s responsibility to determine if the pipe mentioned in your inquiry is directly associated with the compressor and experiences the same service
environment as inferred for compressors in NACE MR0175/ISO 15156-3:2003 Table A.6.
e) The Maintenance Panel cannot review individually designed equipment and pressure stations to make this interpretation.
2a) The manufacturer and user may consider documenting previous experience with pipelines in accordance with NACE MR0175/ISO 15156-1:2001 Paragraphs 8.2 and 9.0.
b) NACE MR0175/ISO 15156-1:2001 provides minimal requirements for these issues and the user is ultimately responsible for ensuring the alloy in final fabricated form has adequate resistance to the types of cracking listed in the Scope 1.0 of NACE MR0175/ISO 15156-1:2001.
3. The ISO Maintenance Panel cannot comment on the suitability of using the 304L SS materials compared to alternative alloys.
A.2.2, Table A.6
The revised version of Table A.6 is included in Reference 3 QUESTION:
SUBJECT: Paragraph 11.4.7 of NACE MR0175-2003 Standard
QUESTION: It is not clear whether or not the word "restrictions" as used in paragraph 11.4.7 of NACE MR0175-2003 includes any environmental restrictions.
Does Paragraph 11.4.7 provide an exemption to all of the environmental restrictions or limits detailed in Paragraph 4.2.2 in cases in which an austenitic stainless steel material has been selected for use in compressors in sour environments?
QUESTION: If the answer to the former question is no, are all of the environmental restrictions detailed in Paragraph 4.2.2 of NACE MR0175-2003 included in the word
"restrictions" as used in Paragraph 11.4.7?
(MP INQUIRY #2003-33) ANSWER:
NACE MR0175/ISO 15156 provides a clear interpretation in Table A.6 that only the metallurgical limits in Paragraphs 4.2 and 4.2.1 apply. Environmental restrictions do not apply. No data have been submitted to verify resistance to cracking in the presence of elemental sulfur.
QUESTION:
As a manufacturer of reciprocating compressors, we supply machines for
compressing sour gas sometimes with a H2S partial pressure up to 10 bar. Before NACE Standard MR0175-2003 came into force, compressor components like valves, valve cages as well as packing cups were manufactured out of austenitic stainless steel to prevent corrosion.
The 2003 edition of MR0175 now contains many restrictions regarding the use of austenitic SS, limiting the H2S partial pressure and temperature to very low values (see page 9, item 4.2.2). Under these circumstances (max. temperature 60°C) these materials are not any more applicable for the compression part.
On the contrary, the use of austenitic SS (UNS S31635/1.4571) acc. EN ISO 15156-3:2003 is allowed--presumed the required heat treatment has been carried out (see page 19, Table A.6). In order to avoid surface corrosion we furthermore intend to use austenitic SS. But by doing so we are contradicting the NACE standard requirements--the standard that is mostly quoted by our customers. We ask for clarification on your part.
(MP INQUIRY #2005-19) ANSWER:
For your information
ISO 15156-1, ISO 15156-2, and ISO 15156-3 (and their EN versions) all have NACE versions with identical technical content; they are:
NACE MR0175/ISO 15156-1, NACE MR0175/ISO 15156-2, and NACE MR0175/ISO 15156-3
These NACE/ISO documents replace all earlier versions of NACE MR0175 including NACE MR0175-2003.
In addition, there have been a number of inquiries on NACE MR0175/ISO 15156-3, Table A.6 since this standard was published; the answers provided by the ISO 15156 Maintenance Panel are included in the document titled "02. Inquiries and Answers" available on the ISO 15156 Maintenance Web site at
www.iso.org/iso15156maintenance
These answers provide clarification of the intent of Table A.6.
A.2.2, Table A.2 and A.2.3
Note: The revised version of Table A.2 is included in Reference 3.
QUESTION:
The way I read Paragraph 4.2, austenitic stainless steels meeting Paragraph 4.2.1 must be solution-annealed and quenched or annealed and thermally stabilized with a maximum hardness of 22 HRC. (1) Am I correct in assuming these materials must be annealed regardless of hardness? (2) If a construction started with materials in this condition, would it be necessary to anneal again following a welding operation?
(MP INQUIRY #2004-04) ANSWER:
You are correct that materials must meet the requirements of MR0175-2003, Paragraph 4.2 regardless of their hardness. Please see Paragraph 5.3.3 for requirements for welding the austenitic stainless steels. Paragraph 5.3.3 does not specifically require an anneal after welding to meet the requirements of 5.3.3.
The requirements for austenitic stainless steels are now presented in Table A.2, NACE MR0175/ISO 15156; you are correct that the materials must meet the treatment conditions regardless of their hardness (maximum 22 HRC). Please see NACE MR0175/ISO 15156 A.2.3 for requirements for welding austenitic stainless steels.
A.2.3
QUESTION:
My stainless steel sheet material qualifies to Section A.2. I am forming this sheet into tubes and (longitudinally) welding the formed tube without filler metals using an automatic arc welding process (ASTM 249/ASTM 269). After welding the tube is fully annealed per ASTM. My hardness values are all below 22 HRC as required.
A. Is my welded and annealed tubing bound to the welding requirements of A.2.3 and 6.2.2?
B. After annealing, if I now butt weld two ends of the tubing above using the orbital weld (no filler metal) process (no additional anneal), am I now bound to A.2.3 and 6.2.2?
(MP INQUIRY #2004-19 Q2) ANSWER:
A. Yes, this is still a weld even if it was made without filler materials.
B. Yes.
QUESTION:
In Section of Part 3: Table A.2 (austenitic stainless steel) states:
"These materials shall also
-be in the solution-annealed and quenched, or annealed and thermally stabilized heat-treatment condition,
-be free of cold work intended to enhance their mechanical properties, and -have a maximum hardness of 22 HRC."
Whereas for welding in Section A.2.3 it is stated that:
"The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable."
I addition Section 6.2.2.2.2 states that "Hardness testing for welding procedure qualification shall be carried out using Vickers HV 10 or HV 5 methods in accordance with ISO 6507-1 or the Rockwell 15N method in accordance with ISO 6508-1.
The use of other methods shall require explicit user approval."
Q1. Please clarify how the requirement for 22 HRC is interpreted in light of this, i.e., what Vickers (HV 10 or HV 5) or Rockwell (15N) value should be used as a
maximum for weld HAZ and weld metal?
On an associated point, for solid-solution nickel-based alloys (Section A.4) and duplex stainless steels (Section A.7) there are no hardness requirements for materials in the solution-annealed condition (with the exception of one HIP duplex stainless steel alloy). The relevant sections (A.4.3 and A.7.3) on welding state:
"The hardness of the HAZ after welding shall not exceed the maximum hardness allowed for the base metal, and the hardness of the weld metal shall not exceed the maximum hardness limit of the respective alloy used for the welding consumable".
Q2. Please confirm that the interpretation that NACE MR0175/ISO 15156 therefore places no hardness restrictions for welds in these materials is correct.
(MP INQUIRY #2005-13) ANSWER:
(1) NACE MR0175/ISO 15156 provides no guidance for hardness conversion from the Vickers to the Rockwell scales for the austenitic stainless steels, which is then left to an agreement between the manufacturer and the equipment user possibly based on conversion tables made using empirical data; see ISO 15156-3, 6.2.1, Paragraph 2.
(2) There are no hardness limits for the HAZ of welds of corrosion-resistant alloys when there are no hardness limits in the tables or the text of the document for the base materials.
For the weld metal, any hardness limit depends on any hardness limit set for the alloy used as consumable. For matching consumables for solid-solution nickel-based alloys (Section A.4) and duplex stainless steels (Section A.7) there are no hardness limits for weld metal.
A.3 and A.4