NACE MR0175 / ISO 15156 Sour Service Checklist

0%

0 of 27 items complete

12 critical items still open - these are the highest-risk gaps.

Download checklist:

Service conditions

H2S partial pressure, total pressure, pH, chlorides and temperature are stated in the specificationCRITICALService is checked against the threshold for sour service defined in the standard (H2S partial pressure above about 0.3 kPa, or 0.05 psia, in wet gas)CRITICALApplicable environmental severity region or regime is identified for carbon and low alloy steelPresence of elemental sulfur, oxygen and other contaminants is recordedEdition of ISO 15156 or NACE MR0175 required by the customer is identifiedCRITICALMaximum design and operating temperature limits for the material are stated

Material selection

Material grade is listed as acceptable in the relevant part of ISO 15156 for the stated conditionsCRITICALCarbon and low alloy steel pressure parts meet the hardness limit, commonly 22 HRC maximumCRITICALCorrosion resistant alloys, such as austenitic or duplex stainless, are checked against their environmental limitsCRITICALCold worked or heat treated condition is as the standard permitsFree machining grades are excludedCast iron and certain other materials not permitted for pressure parts are excluded

Bolting

Studs and nuts grade is acceptable for sour service, for example A193 B7M with A194 2HMCRITICALBolting hardness is verified and within limitsCRITICALCoating or plating on bolting is allowed by the specificationExternal exposure of bolts to H2S is assessed (exposed versus protected)

Welding and fabrication

Welding procedure qualification includes hardness testing of the weld and heat affected zoneCRITICALWeld and HAZ hardness is within the limit permitted for the base materialCRITICALPost weld heat treatment is performed where required and recordedWeld repairs follow the qualified procedure and are re-testedCold forming and straightening are checked against the permitted degree of cold work

Documentation and verification

Material test reports show heat treatment, strength and hardness for each pressure partCRITICALHardness test locations and methods follow the acceptable practiceProduct marking shows the sour service designation required by the customerCompliance statement for NACE MR0175 / ISO 15156 is signed and references the editionCRITICALSub supplier and casting or forging sources are covered by the same requirementDocumentation is retained with the equipment data book

Any failed critical item means the component is not shown to be suitable for sour service. Hold it and ask a materials engineer to review.

Sour service flags on purchase orders

Optional: a discussion on automating special material requirements in your ERP.

Optional. The tool and every export work without this. No spam.

How to use the checklist

Start with the customer's service data: H2S partial pressure, pH, chlorides, temperature. Then check each component, from body forging to studs. For each, confirm the material is allowed in the standard for those conditions, verify hardness, and make sure the paperwork says so. Export the result and attach it to the purchase order file or supplier audit.

Get written service conditions from the customer
Name the standard edition in the PO
Do not rely on a general statement from the supplier
Include bolting, springs and internals

What the standard is

ISO 15156, published jointly with NACE as MR0175, has three parts: general principles, carbon and low alloy steels, and corrosion resistant alloys. It addresses sulfide stress cracking, hydrogen induced cracking, stress oriented hydrogen induced cracking and related forms. NACE MR0103 is a separate standard for refinery and downstream environments and should not be confused with the upstream standard.

Key practical limits

For carbon and low alloy steel, the commonly cited maximum hardness is 22 HRC, and welds must be qualified to show hardness stays inside the limit. Carbon steel bolting often moves to B7M and 2HM to meet it. Austenitic and duplex stainless, nickel alloys and others each have their own limits on temperature, H2S level and chlorides, so they need an individual check.

Common mistakes

Typical mistakes include accepting a stainless grade without checking chlorides and temperature, assuming standard B7 studs are fine, skipping HAZ hardness testing, and mixing up NACE MR0175 with MR0103. Poor documentation is just as common, a certificate that says compliant without edition or without hardness values.

B7 bolting is not B7M
Check each sub-supplier part
Record hardness values, not just a pass
Re-check when conditions change

Frequently Asked Questions

What is NACE MR0175 / ISO 15156?

It is a standard that lists materials and limits for equipment used in oil and gas production environments containing hydrogen sulfide, to avoid cracking mechanisms such as sulfide stress cracking.

What is the hardness limit for sour service steel?

For carbon and low alloy steels the widely used limit is 22 HRC maximum, with specific rules and exceptions in the standard. Confirm the exact limit for your material in the current edition.

Is MR0175 the same as MR0103?

No. MR0103 addresses sour environments in refining and downstream facilities. MR0175 / ISO 15156 covers oil and gas production environments.

Does this checklist certify compliance?

No. It guides a review. Compliance is declared by the manufacturer against the named edition, supported by material and hardness records, and verified by your materials engineer.

Netray can help flag sour-service lines and required documentation automatically on purchase orders in your ERP. The checklist works without that.

Talk to an Expert Explore More Free Tools

Related Tools

Quality & Inspection

More Compliance & Contracts tools

See all

NACE MR0175 / ISO 15156 Sour Service Compliance Checklist