Read the complete designation
ASTM A105/A105M covers forged carbon-steel piping components for ambient- and higher-temperature pressure service. “A105N” is widely used in valve schedules to indicate A105 supplied in a normalized condition. The N is a heat-treatment condition, not a separate alloy grade with its own ASTM number.
ASTM A350/A350M covers carbon- and low-alloy steel forgings intended primarily for low-temperature service and requiring notch-toughness testing. LF2 is a grade within that specification. A purchase description should therefore read ASTM A350 LF2 and include the required class, edition, impact-test temperature and any supplementary requirements.
| Designation | What it establishes | What remains to be stated |
|---|---|---|
| ASTM A105 | Carbon-steel forging specification and grade | Required heat treatment, project temperature, tests and code rating |
| A105N (project shorthand) | ASTM A105/A105M requested in normalized condition | Certificate wording, actual heat treatment record, temperature and toughness requirements |
| ASTM A350 LF2 | Low-temperature forging specification with notch-toughness basis | LF2 class, impact temperature/energy, heat treatment and project edition |
What normalizing changes - and what it does not prove
Normalizing heats the steel above its transformation range and cools it in air under a controlled procedure. It is used to develop a more uniform and refined microstructure after forging. The material certificate should show the heat-treatment condition required by the order.
The letter N does not prove low-temperature suitability, impact performance, sour-service compliance or a particular valve pressure rating. Those claims require the applicable material results and design-code checks for the exact valve.
Low temperature is a toughness question, not a label swap
As temperature falls, ferritic steels can lose notch toughness. ASTM A350 addresses this risk by requiring notch-toughness testing for its low-temperature grades. The project must still specify the minimum design-metal temperature and any required test temperature, absorbed-energy criteria and lateral-expansion criteria.
Do not substitute LF2 merely because a line is outdoors, and do not retain A105 merely because the operating temperature is normally warm. Start-up, depressurisation, blowdown, ambient exposure and upset conditions can control the minimum metal temperature.
The body grade does not set the complete valve envelope
Stem, wedge or disc, seat, bonnet, bolting, packing and gaskets can impose a narrower temperature or chemical limit than the body. A soft seat or graphite packing choice, for example, must be assessed independently. The lowest permitted component limit governs the assembled valve.
Pressure class also requires a pressure-temperature table for the actual body material group and design standard. A Class 800 marking is not an allowable working pressure at every temperature.
RFQ wording that prevents ambiguity
State the body and bonnet material separately, even when they are intended to match. Add design and operating temperatures, the minimum design-metal temperature, pressure, medium, corrosion allowance if applicable and the required certificate type.
Where LF2 is required, include the LF2 class and impact requirements. Where A105N is required, write “ASTM A105/A105M, normalized” and require the heat-treatment condition on the material certificate. If NACE MR0175/ISO 15156 is relevant, give the environmental limits and hardness requirements; the word “NACE” alone does not define a service basis.
Specification checks
- Write the full ASTM specification, grade, class where applicable and required edition.
- State normalized condition explicitly instead of assuming all A105 is A105N.
- Give minimum design-metal temperature and impact-test requirements for low-temperature service.
- Check bonnet, bolting, trim, packing and gasket limits separately from the body.
- Require traceable material certificates and recorded heat treatment.
Catalogue and RFQ
Standards publisher references
Published by Nordic Valves Ab Oy, the operator of FerraForge. These links describe the publishers’ official scope. Purchase documents must state the edition required by the project and include any amendments or owner specifications.
- ASTM A105/A105M - Carbon Steel Forgings for Piping ApplicationsASTM International · Official specification scope for forged carbon-steel piping components.
- ASTM A350/A350M - Carbon and Low-Alloy Steel Forgings Requiring Notch Toughness TestingASTM International · Official specification scope for low-temperature forged piping components.
- ASME B16.34 - Valves - Flanged, Threaded, and Welding EndASME · Official scope covering valve pressure-temperature ratings, materials, dimensions, testing and marking.
- ISO 15156-2 - Carbon and low-alloy steels for H2S-containing oil and gas environmentsInternational Organization for Standardization · Official scope for selection and qualification of carbon and low-alloy steels against H2S-related cracking in the stated upstream environments.