Description
Chromium-molybdenum-vanadium bolting for elevated temperature
ASTM A193 Grade B16 Alloy Steel Heavy Hex Bolts
ASTM A193 Grade B16 alloy steel heavy hex bolts use chromium-molybdenum-vanadium chemistry for pressure equipment and industrial bolted joints requiring strength at elevated temperature.
What are ASTM A193 B16 heavy hex bolts?
Grade B16 is an ASTM A193 ferritic alloy steel bolting grade developed for high-temperature service. Vanadium additions and controlled heat treatment distinguish it from the more widely used B7 grade and support retention of strength in selected elevated-temperature applications.
A B16 heavy hex bolt is a headed configuration, not a separate material standard. The purchase order should combine ASTM A193 Grade B16 with the required heavy hex dimensional basis, thread, length, compatible nut, coating, service temperature and design code.
Key procurement advantages
ASTM A193 Grade B16 Alloy Steel Heavy Hex Bolts specifications
| Bolting standard | ASTM A193/A193M, ordered edition |
|---|---|
| Grade | B16 |
| Material | Quenched-and-tempered chromium-molybdenum-vanadium alloy steel |
| Service basis | High-temperature or high-pressure service where Grade B16 is specified |
| Head / dimensions | Heavy hex head to ASME B18.2.1 or project drawing |
| Thread system | UNC, UNF or 8UN to ASME B1.1 as ordered |
| Typical supply range | 1/2 through 4 in. diameter; mechanical requirements vary by size |
| Compatible nut | ASTM A194/A194M Grade 4 or Grade 7 heavy hex nut as specified by the design |
| Finish / coating | Plain, black oxide or technically approved project coating |
| Temperature selection | Allowable temperature and stress must be confirmed from the governing design code |
| Documentation | EN 10204 3.1 MTC, heat-treatment, mechanical and dimensional inspection records |
Published ranges are procurement guidance, not a design approval. The purchase order, governing code, standard edition and approved drawing control final dimensions, properties and acceptance criteria.
How to select this grade
| Selection point | ASTM A193 Grade B16 Alloy Steel Heavy Hex Bolts | When to review another grade |
|---|---|---|
| Alloy system | Chromium-molybdenum-vanadium | B7 uses chromium-molybdenum alloy steel |
| Selection driver | Specified elevated-temperature strength | B7 is the more common general pressure-service grade |
| Common nut | ASTM A194 Grade 4 or 7 as designed | ASTM A194 Grade 2H commonly paired with B7 |
| Design check | Confirm code allowable stress at temperature | Do not select either grade from marketing temperature claims alone |
Matching nuts, washers and coatings
Compatible nut selection depends on the governing design and service temperature; ASTM A194 Grade 4 or Grade 7 heavy hex nuts are commonly considered. Confirm thread fit, thermal expansion, washer, coating and lubrication for the complete assembly. The equipment engineer must use code allowable stresses rather than a generic maximum-temperature statement.
Typical applications
| Industry | Typical duty | Why this grade is specified |
|---|---|---|
| Power generation | Turbine auxiliaries, boilers and high-temperature equipment | Cr-Mo-V alloy strength where B16 is specified |
| Refining | Hot process equipment and selected pressure joints | Elevated-temperature bolting capability |
| Petrochemical | Reactors and process machinery | Traceable high-temperature alloy bolting |
| Industrial equipment | Custom high-load headed-bolt connections | Heavy hex geometry and drawing-based manufacture |
Application examples do not replace engineering review. Confirm load, temperature, pressure, environment, joint design, installation method and governing code before selection.
Inspection, testing and documentation
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.
Process records linked to the heat and finished bolt lot.
Tensile, yield, elongation, reduction and hardness verified as applicable.
Head, body, length and thread geometry checked to the order.
Alloy verification and third-party inspection available for critical projects.
RFQ and ordering checklist
- ASTM standard, grade, type and required edition
- Heavy hex dimensional standard or approved drawing
- Diameter, overall length and thread length
- Thread series, pitch and class of fit
- Matching nut and washer standards and grades
- Surface finish, coating, lubrication and color
- Service temperature, environment and design code
- Quantity, marking, packing and delivery destination
- EN 10204 MTC, mechanical, impact, hardness, PMI and NDE requirements
- Third-party inspection or project hold points
Frequently asked questions
What is ASTM A193 Grade B16?
B16 is a heat-treated chromium-molybdenum-vanadium alloy steel bolting grade for high-temperature or high-pressure service and other special-purpose applications.
How is B16 different from B7?
B16 contains vanadium and has different heat-treatment and mechanical requirements. It is selected for particular elevated-temperature designs, while B7 is more broadly used for pressure service.
Which nuts are used with B16 heavy hex bolts?
ASTM A194 Grade 4 or Grade 7 heavy hex nuts are common choices, but the governing equipment or piping design controls the final assembly.
What is the maximum service temperature for B16?
There is no universal marketing value that replaces engineering design. The allowable stress, temperature, diameter and design code must be evaluated for the specific joint.
Can B16 bolts be made to custom lengths?
Yes. Diameter, overall length, thread length and heavy hex head geometry can be manufactured to an approved drawing and the ordered standard requirements.
Request a heavy hex bolt quotation
Send the standard, grade, drawing, size, assembly, service condition, quantity and documentation requirements for technical review.
