Technical information

General information about NACE standards
For sour gas applications with WIKA products
WIKA data sheet IN 00.21

General information
This technical information refers to two publications in thearea of material requirements. Here MR stands for "MaterialRequirements".
■■ NACE 1) MR0175“Petroleum and natural gas industries. Material for use in
H2S-containing environments in oil and gas production.”■■ NACE 1) MR0103“Materials resistant to sulphide stress cracking incorrosive petroleum refining environments.”■■ Only for pressure gauges, pressure transmitters,
diaphragm seals and thermowellsFig. left: Bourdon tube pressure gauge model 232.30
Fig. right: Diaphragm seal, flange connection
model 990.27

Description
Natural gas and crude oil, as raw materials, contain greateror lesser high levels of hydrogen sulphide (H2S). If there is aminimum amount of H2S and a minimum total pressure, sucha mixture is recognised as “sour gas” or “sour oil”.
Both standards describe the corrosion properties of metals in
the presence of H2S under different corrosion mechanisms.
Firstly, hydrogen-induced stress cracking corrosion isconsidered. This is greatest at room temperature and is thefocus of MR0103. A typical application for this standard isdownstream processing in a refinery.
Secondly, chlorine-induced stress cracking corrosion under
the influence of H2S is considered. This is aided at higher
temperatures and is described by NACE MR0175. A typicalapplication is the production of oil and gas.
1) The term “NACE” refers to an organisation (National Association of Corrosion
Engineers), which primarily deals with any form of corrosion. The results of their work
are published in many publications as NACE standards and updated regularly. The
headquarters of this organisation is in Houston, Texas/USA.

WIKA data sheet IN 00.21 ∙ 12/2018

Application example:
Pressure transmitter models E-10 and E-11

Thermowells in various design
Page 1 of 3

The NACE MR0175 standard is represented in theISO 15156 standard (part 1 - 3) internationally valid. Thisdeals with technical issues regarding corrosion of materials
during the extraction and processing of natural gas andcrude oil. The ISO 15156 standard, Part 3, describes theuse of corrosion-resistant metals and complies with toNACE MR0175.

NACE MR0103
This standard is similarly constructed and can also be
implemented for WIKA products if a customer wishes. It
defines the material requirements and temperature limits forapplications in refineries.

NACE MR0175
NACE MR0175 (ISO 15156-3) describes, according to theapplication, for the various material groups, the relevant
requirements for each individual material and the maximum
permissible temperature limits (see table).

Material selection
In sour gas applications, the corrosion properties of metals
depend on the environmental conditions (pH value, chloridecontent, H2S concentration and temperature limits) and themaximum strength of the materials. For different materials
there are different strength requirements.
In accordance with the standard, ISO 15156-1/section 5“General principles”, it is the responsibility of the user tospecify which material is suitable for the application.
With knowledge of the above-mentioned environmental
conditions, WIKA can make recommendations on theselection of materials.
If the details of the environmental conditions are notadequately known, WIKA specifies the operating
conditions for ISO 15156-3 under the assumption of criticalenvironmental conditions.
On this basis, therefore, only the lowest maximum processtemperature can be confirmed.

Example:For nickel-based alloys such as HC276, in a work-hardened
condition, without knowledge of the environment conditions,a maximum temperature of 132 °C will apply, whereby,at a given partial pressure of H2S of less than 200 kPa, amaximum temperature of 232 °C would be possible.
Generally, with its products, WIKA fulfills the strength
requirements (maximum hardness) of materials. Exceptions
are the elements of mechanical pressure gauges. Here, due
to their elastic properties, higher strength is required. WIKA
has demonstrated in detail the suitability of its Bourdon tube
measuring system in accordance with ISO 15156-3 throughindependent laboratory testing up to 120 °C.

The following table gives an example-based overview of the lowest maximum operating temperatures by material and productgroup per “Any equipment and component” in accordance with ISO 15156-3/NACE MR0175.
Product group

Stainless steel 316L

Monel 400

Duplex 1.4462
n/an/an/aElectronic pressure
measuring instruments

n/an/an/an/ano limit 3)

no limit 2)

no limit

max. 232 °C

max. 132 °C

n/aThermowells

no limit 2)

no limit

max. 232 °C

max. 132 °C

n/aMechanical pressure
measuring instruments

Diaphragm sealmax. 120 °C 1)

no limit

Alloy C276

Elgiloy 2.4711

1) Measured using laboratory testing2) Classified using “Instrumentation and control device”: as of 20093) Classified using “Diaphragms, pressure diaphragms, pressure measuring devices and pressure seals”

Even if the NACE standard has no temperature limit, the product-specific details, which can limit the maximum operating
temperature, should be considered.
WIKA data sheet IN 00.21 ∙ 12/2018

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General informationWelding
The welding processes (WPS/PQR) are qualified inaccordance with the appropriate standards (AD 2000
or ASME). One element of the welding procedure tests
is hardness testing of the weld seam. A retrospective
verification of the hardness on the welded product is notprescribed by the NACE standards for cracking-resistantalloys.
Heat treatment following welding
Heat treatment (PWHT) is not mandatory. For certain
materials (e.g. carbon steel) heat treatment can be required
due to technical considerations of the welding.
Hardness values on semifinished productA proof of the hardness values of the semi-finishedproducts is made via the supplier’s 3.1 acceptance test
certificate (except for stainless steel Bourdon tubes and
NiCrCo alloy 2.4668 (Inconel 718) diaphragm elements).

12/2018 EN© 05/2012 WIKA Alexander Wiegand SE & Co. KG, all rights reserved.
The specifications given in this document represent the state of engineering at the time of publishing.
We reserve the right to make modifications to the specifications and materials.

WIKA data sheet IN 00.21 ∙ 12/2018

Page 3 of 3

WIKA Alexander Wiegand SE & Co. KG
Alexander-Wiegand-Straße 30
63911 Klingenberg/GermanyTel.
+49 9372 132-0
Fax+49 9372 132-406
info@wika.de
www.wika.de