What is the difference between L7 and L7M?

Both are impact tested under ASTM A320. L7M adds a maximum hardness requirement on every stud for sour-service resistance, which lowers strength compared with L7.

Which nut is paired with L7M?

Projects commonly pair L7M with ASTM A194 Grade 7M or 7ML nuts. Your specification governs the final pairing.

Do you hold L7M in stock?

EMG supplies L7M buy-to-order. The lead time is quoted per RFQ after material, testing and records are confirmed.

Packed alloy steel stud bolts with heavy hex nuts ready for dispatch

Low-temperature alloy steel

ASTM A320 L7M Stud Bolts

Hardness-controlled L7M stud bolts for low-temperature flanges where sour service rules also apply, quoted buy-to-order with impact test and hardness records.

Request a Quote Configure a kit

BUY-TO-ORDER SUPPLYLEAD TIME QUOTED PER RFQEN 10204 3.1 / 3.2 RECORDS

GRADE OVERVIEW

A320 L7M stud bolts, specified correctly.

L7M combines the low-temperature impact testing of ASTM A320 with a hardness cap aligned to NACE MR0175 / ISO 15156, which is why it is commonly specified on LNG and gas processing lines that also carry wet H2S.

Because hardness is restricted, design strength is lower than L7. Confirm the joint calculation and nut grade with your engineer before substituting L7M for L7 or B7M.

View the material reference

GRADE: ASTM A320 Grade L7M
UNS / TYPE: AISI 4140 / 4142 type
MATCHED NUT: ASTM A194 Grade 7M / 7ML
SIZES: 1/4"–6" · M5–M150

WHERE IT IS SPECIFIED

Typical applications

LNG & gas processing

Cold-service flanges where H2S sour-service hardness limits also apply.

Offshore & subsea topsides

Bolting packages specified to project sour-service and impact requirements.

Shutdown spares

Matched L7M/7M kits prepared against line lists for planned outages.

WHAT TO PUT ON YOUR RFQ

Quoted right the first time.

Size & length

Diameter from 1/4" to 6" or M5 to M150, thread form (UNC/8UN or metric), and length measured per ASME B16.5 / B16.47 or your drawing for L7M.

Nuts, washers & coating

Specify matched heavy hex nuts, through-hardened washers and any coating, such as Xylan/PTFE, so the kit is quoted as one traceable package.

Records & inspection

State EN 10204 3.1 or 3.2, PMI, hardness or impact testing and any project ITP so certificates are confirmed before order.

QUESTIONS

A320 L7M FAQs

REQUEST A QUOTE

Send your A320 L7M requirement.

Send sizes, quantities, nuts, coating, certificates and required date, or attach a line list or drawing. EMG confirms sourcing, records and lead time against your RFQ.

Sizes & lengths

Diameter, thread, length and quantity per line.

Grade & nuts

ASTM A320 Grade L7M with ASTM A194 Grade 7M / 7ML.

Records

EN 10204 3.1 / 3.2, PMI and testing as specified.

RELATED GRADES

Compare other stud bolt grades

UNS S31600