Technical Specifications

Quick reference for the technical decisions that drive weld neck flange selection. Material grade summary, NACE hardness, impact testing, API 6A material classes.

Material Grade Quick Reference

Grade	Type	Min Yield	Min Tensile	Typical Use
A105	Forged carbon	36 ksi	70 ksi	General pressure
A350 LF2	Carbon impact	36 ksi	70 ksi	Low temp -50 F
A694 F60	High-yield carbon	60 ksi	75 ksi	Pipeline X60 mate
F304L	Austenitic stainless	25 ksi	70 ksi	General corrosion
F316L	Mo stainless	25 ksi	70 ksi	Chloride resistance
F22	2.25 Cr 1 Mo	30 ksi	75 ksi	Hot service to 1100 F
F91	9 Cr 1 Mo V Nb	60 ksi	85 ksi	Power main steam
C-276	Hastelloy nickel	41 ksi	100 ksi	Chloride and acid corrosion
Inc 625	Ni-Cr-Mo	60 ksi	120 ksi	FGD and acid service
2205	Duplex SS	65 ksi	90 ksi	Chloride pitting
A516-70	Pressure plate	38 ksi	70 ksi	Blind and ring

API 6A Material Class Summary

AA, BB: standard service. AA general, BB with charpy impact for low temperature.
CC, DD: NACE MR0175 sour service. Controlled hardness and chemistry.
EE: sour service plus higher strength plus low temperature.
FF, HH: severe sour service with the most restrictive chemistry and hardness limits.

NACE Hardness Limits

For wet H2S service per NACE MR0175 / ISO 15156:

Carbon and low alloy steels: 22 HRC (about 248 HV) maximum
F22 and F91 alloy: per supplementary annex, typically 22 HRC max post-PWHT
F304L and F316L stainless: 22 HRC maximum plus ferrite content limits
Duplex 2205 and 2507: 28 HRC maximum, separate annex
Nickel alloys (C-276, Inconel 625): typically 35 HRC max, see specific NACE annex

Charpy Impact

Common test temperatures and minimum absorbed energy: A350 LF2 at -50 F, 13 ft-lb min avg. A350 LF3 at -150 F, 15 ft-lb min. A694 F60 at -20 F, 20 ft-lb min. API 6A class EE typically tested at -50 F or lower with project-specific energy requirements.

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Phone: 281-484-8325

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