Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
21CrMoV5-7 Pressure Vessel Bolts (EN 10269 / 1.7709)
21CrMoV5-7 pressure vessel bolts are specified into unfired pressure-vessel bolting under VdTUV Wb 350 (German approval), ASME BPVC Section VIII Division 1 (US ASME-stamped vessels via dual-cert to ASTM A193 B16), and European PED-compliant vessels using EN 10269 base qualification. The Cr-Mo-V Q+T chemistry handles continuous service to 550 deg C with sustained creep margin.
Service Envelope
| Pressure vessel class | Design temp | Bolting standard |
|---|---|---|
| VdTUV Wb 350 unfired | up to 550 deg C | 21CrMoV5-7 with Wb 350 approval |
| ASME BPVC Section VIII Div 1 | up to 540 deg C | ASTM A193 Grade B16 (dual-cert) |
| European PED (general) | up to 550 deg C | 21CrMoV5-7 / EN 10269 |
| Cryogenic / low-temp | below -29 deg C | Outside envelope; ASTM A320 or austenitic |
Bolting Form Factors Used
- Stud Bolts: flange bolting on vessel manways, channel-heads and inspection ports
- Heavy Hex Bolts: main pressure-vessel flange bolting to ASME B18.2.1
- Tap Studs: blind-tap-end bolting on selected vessel designs
- Heavy hex nuts to ASME B18.2.2 or DIN 6915 / ISO 7414
Mechanical Floors for Pressure Vessel Bolts Service
| Property | Value | Condition |
|---|---|---|
| Tensile (Rm) | 700 to 850 MPa | RT, Q+T |
| 0.2 percent proof stress (Rp0.2) | ≥550 MPa | RT, Q+T |
| Elongation A5 | ≥16 percent | RT, longitudinal |
| Charpy V impact (KV) | ≥63 J | 20 deg C |
| 0.2 percent proof at 500 deg C | ≥450 MPa | elevated-temp |
| Hardness | 210 to 250 HBW | Q+T |
Standards Anchor
21CrMoV5-7 pressure-vessel bolting to EN 10269. Wb 350 approval per VdTUV Wb 350 on call-out for German-built or TUV-certified vessels. ASME dual-cert to ASTM A193 Grade B16 for ASME BPVC pressure vessels.
When to Step Up the Grade
For service above 550 deg C metal temperature, the design steps up to Durehete 1055 (Alloy T41 / Werkstoff 1.7729 / 20CrMoVTiB4-10) with Ti+B microalloying for extended creep envelope. For heavier sections of the same temperature window, sister grade 21CrMoV5-11 (1.8070) provides extended hardenability.
Frequently Asked Questions
Q. Is VdTUV Wb 350 approval required for all 21CrMoV5-7 pressure-vessel bolting?
Only for German-built or TUV-certified vessels at design temperature above 500 deg C. For other PED-notified bodies or for ASME pressure vessels, the EN 10269 base qualification (with cross-reference to ASTM A193 B16) is sufficient.
Q. Can I use 21CrMoV5-7 on a cryogenic pressure vessel?
No. The Cr-Mo-V Q+T chemistry has poor impact toughness below -29 deg C. Cryogenic pressure-vessel bolting uses ASTM A320 grades (B7, B8M) or austenitic alternatives.
Q. What is the matched-nut specification for pressure-vessel bolting?
Heavy hex nuts to ASME B18.2.2 (Unified inch) or DIN 6915 / ISO 7414 (metric heavy hex) in matched-grade 21CrMoV5-7. Standard hex nuts to DIN 934 / ISO 4032 acceptable for lower-pressure service.
Q. Are pressure-vessel bolts inspected with EN 10204 type 3.2?
Yes, as standard practice. Type 3.2 with Lloyd's Register, DNV, BV, SGS or TUV witness inspection is required for pressure-vessel bolting on PED-notified and ASME-stamped vessels.
Related Applications
More 21CrMoV5-7 service applications: Steam Turbine Bolts · Gas Turbine Bolts · Power Plant Bolting · Boiler Bolts · Heat Exchanger Bolts · Fired Heater Bolts · Petrochem Reactor Bolts. Back to the 21CrMoV5-7 Alloy Hub.
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