설명
Controlled-hardness low-temperature alloy bolting
ASTM A320 L7M Low Temperature Stud Bolts
ASTM A320 Grade L7M fully threaded stud bolts combining low-temperature impact requirements with grade-specific hardness control for project-defined flange bolting service.
빠른 답변
ASTM A320 L7M stud bolts are low-temperature alloy-steel bolting components with impact-testing and controlled-hardness requirements. They are often specified where both low-temperature toughness and environmental cracking controls matter, but NACE MR0175/ISO 15156 compliance must be ordered and reviewed separately.
Product at a glance
무엇입니까? ASTM A320 L7M 스터드 볼트?
L7M is a distinct ASTM A320 low-temperature bolting grade requiring control of heat treatment, hardness and impact properties. It is not produced by simply applying a coating or different marking to L7 material. Manufacturing and testing must support the finished Grade L7M order.
Projects may pair L7M studs with ASTM A194 Grade 7M heavy hex nuts and may add sour-service requirements. The exact standard editions, hardness criteria, impact-test temperature, nut qualification, coating restrictions and inspection scope must be written into the purchase order.
ASTM A320 L7M stud bolt specifications
| 재료 | Heat-treated, controlled-hardness alloy steel to ASTM A320/A320M L7M |
|---|---|
| Low-temperature test | Charpy impact testing to the ordered test temperature and criteria |
| 구성 | Fully threaded stud bolt; custom double-end studs by drawing |
| 스레드 | 유엔사, 8UN or project-specified series and class to ASME B1.1 |
| 치수 | ASME B18.31.2, flange bolting schedule or approved drawing |
| Matching nuts | ASTM A194/A194M Grade 7M when specified and compatible |
| Special service | NACE MR0175/ISO 15156 only when explicitly stated and reviewed |
| 선적 서류 비치 | MTC, impact and hardness results, 치수, traceability and coating records |
최종 치수, 공차, 열처리, 기계적 성질, 충격 또는 경도 요구 사항, coating and acceptance criteria follow the purchase order and the contractually specified standard edition.
Why specify this grade?
Specify L7M when the approved material class requires an A320 low-temperature grade with controlled hardness. This makes it suitable for tightly controlled bolting packages where low-temperature toughness and hardness documentation are both procurement requirements.
Critical engineering note
Neither the L7M marking nor a generic NACE statement replaces service-condition review. Confirm H2S partial pressure, 염화물, pH, 온도, material condition, coating process, hardness test method and the owner specification before manufacture.
마개, nut and finish options
일반적인 애플리케이션
품질, 검사 및 문서화
L7M documentation should make both low-temperature impact qualification and hardness control visible to the purchaser. Optional coating, NACE and third-party requirements are recorded as separate order attributes.
- EN 10204 3.1 material test certificate when ordered
- Heat-number and manufacturing-batch traceability
- Chemical composition and mechanical-property results
- Hardness testing at the frequency required by the ordered grade
- Charpy impact testing for low-temperature grades as specified
- Dimensional inspection and calibrated thread gauging
- Coating thickness or surface-condition inspection when applicable
- Third-party inspection, marking and export packing by agreement
견적에 필요한 정보
- ASTM standard, grade and contractually required edition
- Stud diameter, 전체 길이, thread series and thread class
- Quantity and whether two nuts per stud are required
- Matching nut specification, 등급, style and finish
- Plain, coated or plated finish and the approved coating system
- Design temperature, impact-test temperature and sour-service requirements when relevant
- MTC, PMI, 경도, 영향, coating and third-party inspection requirements
- 배송지, packing method and required schedule
자주 묻는 질문
What is the difference between L7 and L7M?
L7M is a separate ASTM A320 grade with controlled-hardness requirements in addition to low-temperature qualification. L7 should not be substituted for L7M without approval.
Do L7M stud bolts automatically meet NACE MR0175?
아니요. NACE MR0175/ISO 15156 compliance depends on the material condition, environment, applicable edition and project requirements and must be specified separately.
Which nuts match A320 L7M studs?
ASTM A194 Grade 7M heavy hex nuts are commonly specified. Confirm their impact qualification, 경도, 치수, finish and documentation in the order.
Can L7M studs be supplied with a fluoropolymer coating?
Yes when approved by the purchaser. The coating process, friction coefficient, 두께, temperature capability, hydrogen controls and service restrictions must be defined.
Related stud bolt products
Reference standards
Material requirements are controlled by ASTM A320/A320M. Matching heavy hex nut requirements are specified separately under ASTM A194/A194M 해당되는 경우. Thread form and stud dimensions may reference ASME B1.1 그리고 ASME B18.31.2, subject to the purchase order. Always state the required edition instead of assuming the latest edition applies to an existing project.
기술 견적 요청
Send your flange bolting schedule, bill of materials, 도면 또는 프로젝트 사양. SASA FLANGE 성적을 검토할 것이다, 견과류, 스레드, 치수, 마치다, 견적 전 문서 및 배송 요구 사항.
