説明
Impact-tested alloy steel bolting for low-temperature service
ASTM A320 Grade L7 Alloy Steel Heavy Hex Bolts
ASTM A320 Grade L7 alloy steel heavy hex bolts are impact-tested, quenched-and-tempered fasteners for low-temperature pressure vessels, バルブ, フランジ, fittings and industrial equipment.
とは何ですか ASTM A320 L7 heavy hex bolts?
ASTM A320/A320M covers alloy steel and stainless steel bolting for low-temperature service. Grade L7 is a ferritic alloy steel grade with mechanical properties broadly comparable to B7 in common sizes, plus low-temperature Charpy impact requirements that address toughness in cold service.
When a headed bolt is required, Grade L7 can be manufactured with a heavy hex head to the dimensional basis stated on the order. The design minimum metal temperature, impact-test temperature, 検体の要件, nut toughness and complete joint specification must be provided before manufacture.
Key procurement advantages
ASTM A320 Grade L7 Alloy Steel Heavy Hex Bolts specifications
| Bolting standard | ASTM A320/A320M, ordered edition |
|---|---|
| 学年 | L7 |
| 材料 | Quenched-and-tempered chromium-molybdenum alloy steel |
| Service basis | Low-temperature pressure service with required impact testing |
| Head / 寸法 | Heavy hex head to ASME B18.2.1 or project drawing |
| Thread system | UNC, UNF or 8UN to ASME B1.1 注文どおり |
| Typical supply range | 1/2 を通して 4 で. diameter; size and impact-test requirements subject to review |
| Compatible nut | ASTM A194 学年 4 or Grade 7 heavy hex nut with required impact testing when specified |
| Compatible washer | ASTM F436 hardened washer or project-specified washer suitable for the service |
| Impact testing | Charpy V-notch energy and test temperature to the ordered A320 and project requirements |
| ドキュメント | EN 10204 3.1 MTC, Charpy results, ヒートトレーサビリティ, mechanical and dimensional reports |
Published ranges are procurement guidance, 設計承認ではありません. The purchase order, governing code, standard edition and approved drawing control final dimensions, properties and acceptance criteria.
How to select this grade
| 選定のポイント | ASTM A320 Grade L7 Alloy Steel Heavy Hex Bolts | When to review another grade |
|---|---|---|
| Primary service | Low-temperature pressure equipment | A193 B7 for high-pressure or elevated-temperature service |
| Impact testing | Required to the ordered L7 basis | Not the defining B7 requirement |
| Common nut | A194 Grade 4 または 7 with impact requirements as ordered | A194 Grade 2H commonly used with B7 |
| Selection input | Design minimum temperature and Charpy criteria | プレッシャー, temperature and equipment specification |
マッチするナット, washers and coatings
Cold-service performance depends on the entire assembly. Specify impact-tested ASTM A194 学年 4 or Grade 7 heavy hex nuts where required, compatible hardened washers, and the project test temperature. A room-temperature nut or unverified replacement can undermine the low-temperature bolting specification.
代表的な用途
| 業界 | 典型的な義務 | Why this grade is specified |
|---|---|---|
| LNG | Liquefaction, storage and transfer equipment | Impact-tested alloy steel for specified low temperatures |
| Refrigeration | Compressors, vessels and cold piping equipment | Verified toughness below ambient temperature |
| Natural gas | Cold-climate and low-temperature process skids | Traceable L7 material and impact records |
| 化学処理 | Low-temperature valves and pressure equipment | Heavy hex headed configuration with cold-service documentation |
Application examples do not replace engineering review. Confirm load, 温度, プレッシャー, environment, joint design, installation method and governing code before selection.
検査, テストと文書化
SASA FLANGE can prepare a project-specific inspection and documentation package. Requirements must be agreed before manufacture so the test frequency, traceability and acceptance criteria are built into the production route.
試験温度, absorbed energy and specimen orientation recorded as ordered.
Properties verified for the finished-product diameter and heat-treatment condition.
Bolt, nut and washer records linked to the ordered assembly.
Head, 長さ, body and thread gauging documented for project acceptance.
RFQ and ordering checklist
- ASTM規格, 学年, type and required edition
- Heavy hex dimensional standard or approved drawing
- 直径, overall length and thread length
- Thread series, pitch and class of fit
- Matching nut and washer standards and grades
- 表面仕上げ, コーティング, lubrication and color
- 使用温度, environment and design code
- 量, マーキング, packing and delivery destination
- EN 10204 MTC, mechanical, インパクト, 硬度, PMI and NDE requirements
- Third-party inspection or project hold points
よくある質問
とは何ですか ASTM A320 L7 heavy hex bolts?
They are quenched-and-tempered alloy steel headed bolts with low-temperature impact requirements for pressure equipment and special cold-service applications.
What is the difference between A320 L7 and A193 B7?
L7 adds low-temperature Charpy impact requirements. B7 is primarily specified for high-pressure or elevated-temperature service without L7 being automatically interchangeable.
Which nut is used with L7 bolts?
ASTM A194 学年 4 or Grade 7 heavy hex nuts are commonly specified, with supplementary impact testing when required by the low-temperature design.
Is L7 suitable for LNG service?
It is widely considered for LNG and low-temperature equipment, but the materials engineer must confirm the design temperature, impact-test criteria, joint design and applicable code.
Which documents prove low-temperature compliance?
Request the EN 10204 3.1 MTC, Charpy impact report, heat-treatment records, 機械的な結果, heat traceability and dimensional inspection.
Request a heavy hex bolt quotation
標準を送る, 学年, drawing, サイズ, assembly, service condition, quantity and documentation requirements for technical review.
