Specifying Sulphur Limits for Carbon and Low Alloy Steels to Comply with NACE MR0175/ISO 15156

At OGC Energy, we specialize in assisting clients with specifying sulphur limits for carbon and low alloy steels in order to ensure compliance with NACE MR0175/ISO 15156. Section 8 of NACE MR0175/ISO 15156-2 emphasizes the significance of steel chemistry and manufacturing route in determining the probability of hydrogen-induced cracking (HIC) and sulfide stress cracking (SWC). The level of sulfur in carbon and low alloy steels is particularly important in this regard.

Our team at OGC Energy helps clients develop material specifications that precisely define sulfur contents to meet the requirements of NACE MR0175/ISO 15156. We take into account integrity threats throughout the service life, including HIC, SWC, and sulfide stress-oriented hydrogen-induced cracking (SOHIC). Additionally, we provide guidance to clients who need clarification on sulfur requirements during fabrication, especially when project specifications are not available as a reference.

You can rely on us to help you make informed decisions regarding sulfur limits and compliance with NACE MR0175/ISO 15156. Contact us today for assistance.

Sulfur Restrictions for ASTM-A105 Carbon Steel Forgings and ASTM-A216 Castings

Question:

The NACE MR0175/ISO 15156 standard does not explicitly mention sulfur restrictions for carbon steel forgings (ASTM-A105) and castings (ASTM-A216), which are widely used in the oil and gas processing industry. These specifications are fundamental to approximately 75% to 90% of construction materials, including flanges, fittings, valves, and rotating machinery casings. Paragraph A.2.1.3 of the standard mentions certain acceptable carbon steels subject to revised or additional restrictions, but it does not provide clear guidance for these two specifications. The original ASTM standards allow sulfur content up to 0.040% for ASTM-A105 and up to 0.045% for ASTM-A216. However, Section 8 of NACE MR0175/ISO 15156 states that conventional forgings with sulfur levels below 0.025% and castings are generally not considered sensitive to HIC or SOHIC. This implies that ASTM-A105 forgings are acceptable if sulfur is limited to 0.025% and hardness is below 187 HBW. Castings have no additional sulfur limit beyond the specification base limit (e.g., 0.045% for ASTM-A216). While the document references many casting and forging grades, it does not adequately address these two crucial materials. Can NACE provide clear mention of these materials with any applicable limitations?

Answer:

The NACE MR0175/ISO 15156 standard does not include specific information about the “limitations” of ASTM-A105 and ASTM-A216 in the manner you requested. It is beyond the scope of the standard to provide detailed limitations for individual steel specifications.

Many steels, including ASTM-A216, are not individually listed in NACE MR0175/ISO 15156-2. As stated in A.2.1.1 General, Paragraph 3:

“The majority of steels that comply with the general requirements of A.2 are not individually listed; however, for convenience, some examples of such steels are listed in Table A.2, Table A.3, and Table A.4.” A.2.1.1 primarily focuses on sulfide stress corrosion resistance.

When any additional restrictions are mentioned (as seen in Section 8 regarding HIC/SWC resistance), they apply to any carbon or low alloy steel covered by the text

Contact OGC Energy for assistance with implementation of NACE MR0175