Описание
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.
Быстрый ответ
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
Что такое ASTM A320 Шпильки L7M?
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
| Материал | Heat-treated, controlled-hardness alloy steel to ASTM A320/A320M L7M |
|---|---|
| Low-temperature test | Charpy impact testing to the ordered test temperature and criteria |
| Конфигурация | Fully threaded stud bolt; custom double-end studs by drawing |
| Threads | UNC, 8UN or project-specified series and class to ASME B1.1 |
| Размеры | 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 |
| Документация | МТС, impact and hardness results, размеры, traceability and coating records |
Окончательные размеры, допуски, термическая обработка, механические свойства, Требования к ударной нагрузке или твердости, 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, хлористый, pH, температура, material condition, coating process, hardness test method and the owner specification before manufacture.
Stud, nut and finish options
Типичные применения
Качество, осмотр и документация
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
- Сторонняя проверка, marking and export packing by agreement
Информация, необходимая для предложения
- ASTM standard, grade and contractually required edition
- Stud diameter, общая длина, thread series and thread class
- Quantity and whether two nuts per stud are required
- Matching nut specification, оценка, style and finish
- Plain, coated or plated finish and the approved coating system
- Design temperature, impact-test temperature and sour-service requirements when relevant
- МТС, PMI, твердость, влияние, coating and third-party inspection requirements
- Место доставки, packing method and required schedule
Часто задаваемые вопросы
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?
Нет. 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, твердость, размеры, 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, толщина, 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 when applicable. Thread form and stud dimensions may reference ASME B1.1 и 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.
Запросить техническое предложение
Send your flange bolting schedule, bill of materials, чертеж или спецификация проекта. SASA FLANGE проверю оценку, орехи, нити, размеры, finish, Требования к документации и доставке перед предложением.
