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What is B16 bolts material?
Quick answer
- Grade
- B16
- Material
- Cr-Mo-V alloy steel, quenched & tempered
- Matching nut
- A194 4 / 7
- Typical use
- High-temperature steam flanges
Technical summary
- Grade
- B16
- Material
- Cr-Mo-V alloy steel, quenched & tempered
- Matching nut
- A194 4 / 7
- Dimensions
- ASME B18.31.2 (studs), B18.2.1 (bolts)
- Certificates
- EN 10204 3.1; 3.2 on request
What is the chemical composition of B16?
| Element | Limit (%) |
|---|---|
| C | 0.36 – 0.47 |
| Mn | 0.45 – 0.70 |
| P | 0.035 max |
| S | 0.040 max |
| Si | 0.15 – 0.35 |
| Cr | 0.80 – 1.15 |
| Mo | 0.50 – 0.65 |
| V | 0.25 – 0.35 |
| Al | 0.015 max |
What are the mechanical properties of B16?
| Size / class | Tensile | Yield | Elong. | R of A | Hardness |
|---|---|---|---|---|---|
| Up to 2½" | 860 MPa (125 ksi) | 725 MPa (105 ksi) | 18% | 50% | 321 HBW / 35 HRC |
| Over 2½" to 4" | 760 MPa (110 ksi) | 655 MPa (95 ksi) | 17% | 45% | 321 HBW / 35 HRC |
| Over 4" to 8" | 690 MPa (100 ksi) | 586 MPa (85 ksi) | 16% | 45% | 321 HBW / 35 HRC |
Where are B16 bolts used?
- High-temperature steam flanges
- Turbine and valve bolting
- Refinery hot-service joints
Selecting bolting for your joint
Bolting must suit the joint's temperature, pressure, environment and gasket. Coatings change the friction factor, so tightening torque must be recalculated. For sour service, hardness-controlled grades (B7M / 2HM) apply under NACE MR0175 / ISO 15156. See the bolting selection guide and flange types & classes.
What to include in your enquiry
- Grade and specification
- Diameter × length and thread series (UNC / 8UN / metric)
- Nuts and washers per bolt
- Coating and colour
- Quantity per size, or your flange schedule
- Certificates (3.1 / 3.2) and tests
Frequently asked questions
Why use B16 instead of B7?
B16 keeps its clamping load better at elevated temperature because of its vanadium-modified chemistry, so it's used for hotter flanged joints.
Which standard covers B16?
ASTM A193 / ASME SA-193, with dimensions to the relevant ASME B18 standard.
Can the bolting be coated?
Yes: zinc, hot-dip galvanised, PTFE-based fluoropolymer or zinc-nickel coatings are available on request. Recalculate tightening torque for coated bolting.
Do you supply complete bolting sets for flange schedules?
Yes. Send your flange schedule (size, class, facing, quantity) and we will prepare the stud, nut and washer list.