What is ASTM A320 L7M?

ASTM A320 Grade L7M is a standard material specification for alloy steel bolting materials for pressure vessels, valves, flanges, and fittings for low temperature services. ASTM A320 Grade L7M is heat treated chromium molybdenum alloy steel (AISI 4140/AISI 4140H) with notch toughness properties.

Is B7 the same as Grade 8?

It is also quenched and tempered at 800 F leading to its strength. Grade 8 has 0.28-0.55% carbon, 0.030% max phosphorus, and 0.050% max sulfur….Grade 8.

GRADE	ASTM A193 B7 (Chromium Molybdenum)	GRADE 8 (Heat Treated After Threading)
ROCKWELL HARDNESS	C26-C32	C33-C39

What kind of steel is ASTM A320 grade L7?

ASTM A320 Grade L7 material is chemically equivalent to ASTM B638 grade 660 stainless steel alloy, also known by alloy A286 and UNS S66286, heat treated to achieve properties defined in ASTM A453 specification.

What is the Charpy value of an ASTM A320?

ASTM A320, Grade L7 This grade is intended for low temperature service down to minus 150° F and has a minimum Charpy impact value of 20 ft. lbs. at this temperature. (-50° to 1100° F) ASTM A320, Grade L7M

What kind of bolts are in ASTM A320?

L7 bolts are available through 2-1/2” in diameter. A320 Grade L7 bolts larger than 1/2″ diameter require a Charpy impact test. ASTM A320 Grade B8 Class 1 bolts and threaded studs are manufactured from AISI 304 stainless steel.

Can you use ASTM A193 grade B7 bolts?

Mostly ASTM A193 Grade B7 bolts are selected along with ASTM A194 Grade 2H nuts. However there is no ASTM or other standard where it recommends using A194 Gr. 2H nuts with this bolt. The reason that A194 grade 2H nuts are used more often with A193 grade B7 bolts is simply cost.