HomeValve ComparisonsNACE MR0175 vs NACE MR0103

Valve Comparison Guide

NACE MR0175 vs NACE MR0103 — Sour Service Valve Selection

NACE MR0175 (ISO 15156) vs NACE MR0103: understand the difference for upstream vs refinery sour service. Hardness limits, material qualification, and which standard to specify on your valve datasheet.

Overview

NACE MR0175 / ISO 15156 (Upstream O&G)

NACE MR0175 / ISO 15156 is the primary sour service standard for oil and gas production and transportation. It covers equipment in H₂S-containing hydrocarbon environments — wellheads, pipelines, separators, and offshore production facilities. ISO 15156 is the international version; MR0175 is the NACE International version — both are technically equivalent.

NACE MR0175 / ISO 15156, hardness-tested per Part 2, Section 7 — all body and trim materials ≤22 HRC

NACE MR0103 (Refinery / Downstream)

NACE MR0103 covers materials for hydrogen sulfide service in petroleum refining environments. It was developed specifically for refinery conditions where H₂S is present at elevated temperatures and in conjunction with polythionic acid stress corrosion cracking (PASCC). Conditions are different from upstream oil & gas — typically higher temperature, H₂S + water + cyanides.

NACE MR0103-2012, hardness-tested, max 22 HRC carbon steel, SS 316L sensitisation avoided

Pros & Cons

NACE MR0175 / ISO 15156 (Upstream O&G)

Covers all upstream and midstream wet H₂S environments — wellhead to processing
Internationally recognised — accepted by all major operators including Saudi Aramco, Shell, BP
Three-part structure: Part 1 (general), Part 2 (carbon/low-alloy steel), Part 3 (CRAs)
Hardness limits: max 250 HV10 (22 HRC) for carbon steel, heat-treated WCB and WC6
Annex A (Part 2) defines permitted grades for each H₂S partial pressure and temperature
Required for all sour service pipelines per API 6D latest editions
More comprehensive and complex — more materials require qualification
Not specifically written for refinery internal service — different conditions apply
Does not cover polythionic acid SCC (PASCC) in refinery service

NACE MR0103 (Refinery / Downstream)

Specifically written for refinery H₂S service conditions — accounts for PASCC in austenitic SS
Generally less restrictive than MR0175 for some materials at refinery temperature ranges
Some austenitic SS grades acceptable in MR0103 that require special qualification in MR0175
Widely accepted by refinery clients (IOCL, BPCL, ExxonMobil, Shell refineries)
Not written for upstream or midstream service — do not apply MR0103 to pipeline or production service
Less internationally referenced than MR0175 for upstream projects
Does not cover deepwater or subsea environments

NACE MR0175 / ISO 15156 (Upstream O&G) vs NACE MR0103 (Refinery / Downstream) — Specification Comparison

ParameterNACE MR0175 / ISO 15156 (Upstream O&G)NACE MR0103 (Refinery / Downstream)
Scope / EnvironmentUpstream O&G production and transmission — wet H₂SRefinery and downstream — H₂S at elevated temperature
International Standard EquivalentISO 15156 Parts 1, 2, 3No direct ISO equivalent — NACE only
Hardness Limit (Carbon Steel)Max 22 HRC (250 HV10)Max 22 HRC — similar to MR0175
Covers PASCC (Polythionic Acid SCC)Not specifically — designed for upstreamYes — specifically written for refinery austenitic SS PASCC
Applicability to PipelinesYes — required by API 6D and pipeline codesNo — refinery internal service only
Most Common UseWellhead, gathering system, processing plant, offshoreCrude distillation unit, hydrotreater, amine unit

When to Use Each

Use NACE MR0175 / ISO 15156 (Upstream O&G) when:

Wellhead and X-mas tree valves — sour crude/gas production
Pipeline and gathering system isolation in H₂S-containing gas fields
Gas processing plants — amine absorbers, glycol dehydration
Offshore production facilities — all wetted parts in sour service

Use NACE MR0103 (Refinery / Downstream) when:

Refinery valves in sour crude units — atmospheric distillation, vacuum distillation
Hydroprocessing unit isolation — hydrotreaters and hydrocrackers with H₂S
Refinery amine treatment units — H₂S stripping
Downstream chemical plant H₂S-containing service

Decision Guide

Specify NACE MR0175 / ISO 15156 for all upstream and midstream applications: wellhead, pipeline, gas processing, LNG, and offshore — wherever H₂S is present in oil or gas production streams. Specify NACE MR0103 for refinery internal service — crude unit, hydrotreating, amine treatment. Never apply MR0103 to upstream pipeline service.

Frequently Asked Questions

Can I apply both NACE MR0175 and MR0103 to the same valve?
Yes — a valve can be manufactured to comply with both MR0175 (for the upstream portion of a project) and MR0103 (if it will be installed in a refinery section). The requirements are similar enough that a valve hardness-tested per MR0175 will generally also comply with MR0103. State both standards on the valve datasheet if the valve is intended for service at a refinery that processes sour crude (common in India, Middle East, USA Gulf Coast).

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