NACE MR0175/ISO 15156-2 Sour Service Bolting, Nace Compliant Fasteners

NACE MR0175/ISO 15156 describes general principles and gives requirements and recommendations for the selection and qualification of metallic materials for service in equipment used in oil and gas production and in natural-gas sweetening plants in H2S-containing environments, where the failure of such equipment can pose a risk to the health and safety of the public and personnel or to the environment. It can be applied to help to avoid costly corrosion damage to the equipment itself. It supplements, but does not replace, the This part of NACE MR0175/ISO 15156 addresses all mechanisms of cracking that can be caused by H2S, including sulphide stress cracking, stress corrosion cracking, hydrogen-induced cracking and stepwise cracking, stress-oriented hydrogen-induced cracking, soft zone cracking, and galvanically induced hydrogen stress cracking.

NACE Compliance Bolting Materials

All Bolting Material with maximum hardness 22 HRC is mentioned in the below table which can be used for nace applications

Standard	Specification	Class		UNS NO.
ASTM A193/A193M	Grade B7M	-	-	G41400
	Grade B8	CLASS 1	CLASS 1D	S30400
	Grade B8M			S31600
	Grade B8P			S30500
	Grade B8LN			S30453
	Grade B8MLN			S31653
	Grade B8ML4CuN			S31730
	Grade B8CLN			S34751
	Grade B8C		-	S34700
	Grade B8T			S32100
	Grade B8A			S30400
	Grade B8CA	Class 1A		S34700
	Grade B8CLNA			S34751
	Grade B8MA			S31600
	Grade B8PA			S30500
	Grade B8TA			S32100
	Grade B8LNA			S30453
	Grade B8MLNA			S31653
	Grade B8NA			S30451
	Grade B8MNA			S31651
	Grade B8MLCuNA			S31254
	Grade B8ML4CuNA			S31730
ASTM A320/A320M	Grade L7M	-		G41400
	Grade B8	Class 1		S30400
	Grade B8M			S31600
	Grade B8P			S30500
	Grade B8C			S34700
	Grade B8F			S30300
	Grade B8LN	Class 1B		S30453
	Grade B8MLN			S31653
	Grade B8T			S32100
	Grade B8A			S30400
	Grade B8CA			S34700
	Grade B8MA			S31600
	Grade B8PA			S30500
	Grade B8FA			S30300
	Grade B8TA			S32100
	Grade B8LNA			S30453
	Grade B8MLNA			S31653
ASTM A194/194M	Grade 2HM	-	-	-
ASTM A194/194M	Grade 7M	-	-	-
ASTM A194/194M	Grade 8A, 8CA, 8CLNA, 8MA, 8TA, 8FA, 8PA, 8NA, 8MNA, 8LNA, 8MLNA, 8MLCuNA, 8ML4CuNA, and 9CA	-	-	-

NACE MR0175/ISO 15156-2 Compliance Bolting

Bolting that can be exposed directly to a sour environment, or that is buried, insulated, equipped with flange protectors or otherwise denied direct atmospheric exposure, shall conform to the general requirements of Carbon Steel & Low alloy Steels mentioned below
The behaviour of carbon and low-alloy steels in H2S-containing environments is affected by complex interactions of parameters, including the following:

• Chemical composition, method of manufacture, product form, strength, hardness of the material and its local variations, amount of cold work, heat-treatment condition, microstructure, microstructural uniformity, grain size and cleanliness of the material;
• H2S partial pressure or equivalent concentration in the water phase;
• Chloride ion concentration in the water phase;
• Acidity (pH) of the water phase;
• Presence of sulphur or other oxidants;
• Exposure to non-production fluids;
• Exposure temperature;
• Total tensile stress (applied plus residual);
• Exposure time.

These factors shall be considered when using this part of NACE MR0175/ISO 15156 for the selection of materials suitable for environments containing H2S in oil and gas production systems. Designers and users should be aware that it can be necessary to lower equipment pressure ratings when using SSC-resistant bolting and fasteners. The use of SSC-resistant bolting and fasteners with API flanges shall be in accordance with ISO 10423.

NACE Compliance Bolting Materials

All Bolting Material with maximum hardness 22 HRC is mentioned in the below table which can be used for nace applications.