説明
Hardness-controlled pressure bolting for specified service
ASTM A193 Grade B7M Alloy Steel Heavy Hex Bolts
ASTM A193 Grade B7M alloy steel heavy hex bolts combine chromium-molybdenum bolting chemistry with restricted hardness for pressure-equipment connections where the project requires B7M.
とは何ですか ASTM A193 B7M heavy hex bolts?
Grade B7M is a modified, hardness-controlled version of ASTM A193 グレードB7. It is commonly selected in project specifications that address sulfide stress cracking risk, but the grade name by itself does not establish compliance with NACE MR0175/ISO 15156 or suitability for a particular sour environment.
For a headed product, the order must identify the heavy hex geometry separately from the B7M material grade. Manufacturing sequence, final heat treatment, hardness verification, thread condition, compatible nut and coating require tighter control than a generic alloy steel bolt order.
Key procurement advantages
ASTM A193 Grade B7M Alloy Steel Heavy Hex Bolts specifications
| Bolting standard | ASTM A193/A193M, ordered edition |
|---|---|
| 学年 | B7M |
| 材料 | Heat-treated chromium-molybdenum alloy steel with restricted hardness |
| Hardness limit | 235 HBW or 99 HRB maximum, subject to the ordered standard requirements |
| 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; サイズ, heat treatment and testing subject to review |
| Compatible nut | ASTM A194/A194M Grade 2HM heavy hex nut when specified |
| Finish / コーティング | Plain or project coating qualified for the material, environment and assembly |
| Sour-service status | NACE MR0175/ISO 15156 compliance only when explicitly ordered and verified for the application |
| ドキュメント | EN 10204 3.1 MTC, 100% hardness verification when required, traceability and inspection records |
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 A193 Grade B7M Alloy Steel Heavy Hex Bolts | When to review another grade |
|---|---|---|
| 硬度 | Restricted for Grade B7M | Higher permitted hardness for standard Grade B7 |
| Typical selection | Project-specified hardness-controlled pressure bolting | General high-pressure or elevated-temperature B7 service |
| Common nut | ASTM A194 Grade 2HM | ASTM A194 Grade 2H for B7 |
| Sour-service claim | Requires project-specific NACE/ISO verification | B7 is not automatically sour-service compliant |
マッチするナット, washers and coatings
Pair B7M bolts with the ordered hardness-controlled nut, 一般的に ASTM A194 Grade 2HM. Confirm washer hardness, コーティング, lubricant and installation procedure. If NACE MR0175/ISO 15156 is required, state the environmental limits, 硬さ試験, heat-treatment records and any additional certification on the purchase order.
代表的な用途
| 業界 | 典型的な義務 | Why this grade is specified |
|---|---|---|
| Sour oil and gas | Specified valves, pressure equipment and skids | Restricted hardness where the materials engineer approves B7M |
| 精製中 | Selected H2S-bearing process services | Project-controlled bolting and documentation |
| 化学処理 | Pressure joints with hardness restrictions | Traceable material and final hardness verification |
| メンテナンス | Replacement of existing B7M headed bolting | Grade-for-grade configuration and marking control |
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.
Testing frequency and individual results documented to the ordered requirements.
Final condition and process route controlled for B7M compliance.
Heat and manufacturing lot maintained through marking and packing.
Additional NACE/ISO declarations and third-party review supplied only when ordered.
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
違いは何ですか ASTM A193 B7 and B7M?
B7M is hardness controlled and has different mechanical and processing requirements. It is often specified where sulfide stress cracking risk is considered.
Does B7M automatically comply with NACE MR0175?
いいえ. Compliance depends on the complete material condition, 硬度, environment, product form and project requirements. NACE MR0175/ISO 15156 must be explicitly ordered and verified.
Which nut matches a B7M heavy hex bolt?
ASTM A194 Grade 2HM heavy hex nuts are commonly specified because they provide a compatible hardness-controlled assembly.
Can B7M bolts be coated?
A coating may be supplied only after its chemistry, curing temperature, 厚さ, lubrication and environmental suitability are reviewed against the project specification.
Which certificates should be requested?
Common requirements include EN 10204 3.1 MTC, heat-treatment records, hardness results, dimensional inspection and any project-specific NACE/ISO documentation.
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.
