Section 10 — Material Requirements

Material Hardness Requirements

IPE Engineering Practice IPE-EP-10-2-3

Document number: IPE-EP-10-2-3 · Section: 10 — Material Requirements

SCOPE

• This standard contains hardness requirements for materials used in selected Aggressive Environmental Services (EP 10–2–1) or where Post Weld Heat Treatment is specified by EP 5– 5–1 and EP 7–1–1.
• This Practice covers material hardness requirements for pressure vessels, tankage, piping components, pressure containing machinery parts and valves. It applies to both new equipment and repairs to existing equipment.
• Welding procedures for all equipment shall be developed such that the hardness requirements of this Practice can be satisfied.
• Any deviation to this Practice shall be in accordance with the procedure given in EP 1–1–3.
• An asterisk (*) indicates that decision by the Owner, Owner’s Engineer or Inspector is required, or that additional information is furnished by the Purchaser.

2.0 REFERENCES

The latest edition of the following standards and publications are referred to herein.

STANDARDS AND PUBLICATIONS

DEFINITIONS

• Aggressive Environmental Service (AES) – Process services which result in material degradation such as cracking, scaling, blistering, and severe pitting and/or corrosion. Examples of such services are hydrogen service, wet hydrogen sulfide, cyanides, caustic, amine, and hydrofluoric acid. AES process fluid are defined in EP 10–2–1.
• Hot Hydrogen Rich Service – A service defined as a combination of hydrogen partial pressure and temperature at or below the curve for carbon steel per Figure 1 of API Publication 941, latest edition, and with a hydrogen partial pressure greater than or equal to 100 psia, and temperature greater than or equal to 450°F.
• Inspector – A Engineering Company appointed engineer or inspector.
• Manufacturer – The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a Manufacturer by a contractor or the Owner. An indirect order is one issued to a Manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
• Owner – Engineering Company.
• Owner’s Engineer – A Engineering Company appointed engineer.
• Purchaser – The party placing a direct purchase order. The Purchaser is the Owner’s designated representative.

MATERIAL HARDNESS REQUIREMENTS

• General

NACE RP0472–95 shall be used for hardness testing guidance. This Practice addresses additional requirements.

• Weld Procedure Qualification Hardness Testing
• Hardness testing on a weld procedure qualification shall be performed for all equipment subject to AES service per EP 10–2–1.
• (*) Subject to Owner’s Engineer approval, the hardness test may be performed on a weld procedure qualification for a different test plate material, if the other material is of the same ASTM specification and has a specified tensile strength within 5 ksi of the steel used in the fabrication.
• Per NACE RP0472–95 Paragraph 5.7, the fabricator shall submit PQR and WPS forms that reflect the procedure qualification hardness tests.

• Production Hardness Testing Procedures
• (*) Production hardness tests shall be made per RP 0472–95 Appendix A. Tests should be conducted on clean metal surfaces that have been hand filed or sanded with a coarse grit paper or wheel. A minimum of 1/32 inch shall be removed from the surface. Care should be taken to avoid excessive heating. If approved by the Owner’s Engineer, a grinder may be used to prepare welds for testing. All tests should be conducted after any final bending/straightening/ heat treatment operation, including PWHT. If accessible, hardness tests must be conducted on the metal surface that will be in contact with the process environment as well as the opposite surface. For a repair, if access to the repaired area is not possible, hardness testing may be waived by Owner’s Engineer.
• (*) The production hardness of a component will be determined per ASTM A833, using a portable Brinell hardness tester Alternate hardness tests may be approved by Owner’s Engineer. For example, a full sized Brinell tester may be appropriate for production parts and the use of a Rockwell C tester is required for valve stems.
• A test is defined as a single valid hardness impression for base metal hardness and a set of two valid impressions for weld metal, with one reading centered in the heat affected zone and the other on the weld crown.
• If any individual hardness test exceeds the limits provided in Section 4.4 then a retest is permitted. The retest shall consist of three (3) additional tests taken in the same area as the high test and all additional tests must meet the hardness limit.
• If the hardness exceeds the limits in Section 4.4 after retesting, then the following are required:
• (*) Weld softening heat treatment may be conducted or the Owner’s Engineer contacted. If after additional heat treatment the hardness still exceeds the limits in Section 4.4, then the Owner’s Engineer shall be contacted for review or the component shall be discarded, AND
• The extent of hardness testing shall be one (1) test per weld.
• The extent of production hardness testing shall be per Table 1.
• Hardness Acceptance Levels
• The acceptable limits on hardness for both procedure qualification and production tests are provided in Table 2 .
• The hardness levels stipulated in this Practice shall be used in lieu of those given in NACE MR– 01–75.

5.0 TABLES

TABLE 1

EXTENT OF PRODUCTION HARDNESS TESTING (1)

TABLE 1

EXTENT OF PRODUCTION HARDNESS TESTING (1) (CONTINUED)

NOTES:

• Atmospheric pressure storage tanks and tube to tubesheet welds are exempted from production hardness testing.
• Valve Manufacturer’s certificate of hardness testing of sub–components prior to assembly is acceptable.
• PH = Precipitation Hardened.

TABLE 2

WELD PROCEDURE AND PRODUCTION HARDNESS ACCEPTANCE LEVELS

NOTES:

• Service definitions in EP 10–2–1.
• The same hardness limits apply for weld procedure qualification hardness tests; however, the reading shall be taken

with a Vickers, Rockwell Superficial Hardness (HR 15N) testing or Knoop Microhardness Tester and the values converted to BHN (Brinell).

• Precipitation Hardened per NACE MR–01–75 heat treatment.

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