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 Heavy Hex Bolts (EN 10269 / 1.7709) Cr-Mo-V Q+T Bolting
21CrMoV5-7 heavy hex bolts are oversized-head hex bolts to ASME B18.2.1, machined from EN 10269 1.7709 Cr-Mo-V Q+T bar. The heavy hex head profile (larger across-flats and head height) gives a wider bearing surface for pressure-vessel and refinery-flange bolting where joint preload is high and bearing stress under the head needs to stay below the material yield.
Heavy Hex Bolts Designs and Variants
Heavy hex bolts come in two main classifications: ASME B18.2.1 inch-series (1/2 inch to 4 inch) for ASME-spec flanges and pressure vessels; metric heavy hex (ISO 4014 metric equivalent) (M12 to M64) for European petrochem applications. Both ship with thread engagement length per the joint stack-up.
Size Range
| Standard | Diameter range | Length range |
|---|---|---|
| ASME B18.2.1 (inch) | 1/2 inch to 4 inch | 1 inch to 16 inch |
| Metric heavy hex | M12 to M64 | 40 to 400 mm |
| Special / custom heads | per project drawing | on request |
Mechanical Properties (Q+T, EN 10269)
| 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
Manufactured to EN 10269 for chemistry and mechanicals. Head dimensions to ASME B18.2.1 heavy hex profile. Thread to ASME B1.1 (UN, UNC, UNF) or ISO 261 (metric). Pressure-vessel approval to VdTUV Wb 350. Dual-cert to ASTM A193 Grade B16.
Companion Hardware
Matched-grade Cr-Mo-V companions ship from the same heat lot on call-out: 21CrMoV5-7 nuts, washers, threaded rod, stud bolts and round bar.
Applications
Heavy hex bolts are specified in pressure vessel bolting per ASME BPVC Section VIII Division 1, heat exchanger bolting (channel-head and shell-side), petrochem reactor flange bolting (hydrocracker manway and main flange), steam turbine casing-half-joint bolting, and fired heater bolting for refinery service.
Inspection Documentation
Default delivery is EN 10204 type 3.1 mill test certificate with heat number, melt-shop pour record, chemistry to EN 10269 21CrMoV5-7, room-temperature tensile and 0.2 percent proof stress, elevated-temperature 0.2 percent proof at the design temperature, Charpy V impact at 20 deg C, hardness, full Q+T cycle chart and dimensional report tied to the heat lot. Type 3.2 with Lloyd's Register, DNV, BV, SGS or TUV witness inspection on call-out and standard practice on turbine and pressure-vessel procurement.
Frequently Asked Questions
Q. What is the difference between a standard hex bolt and a heavy hex bolt?
Heavy hex bolts have larger head dimensions (across-flats and head height) to ASME B18.2.1 vs the standard ASME B18.2 hex bolt. The larger bearing area reduces stress under the head on pressure-vessel and refinery-flange joints where preload is high.
Q. Are 21CrMoV5-7 heavy hex bolts approved for ASME pressure vessels?
Yes. They are supplied with dual-certification to EN 10269 and ASTM A193 Grade B16 (an ASME SA-193 approved bolting grade). The dual cert allows specification on either European PED or US ASME BPVC pressure-vessel projects.
Q. What is the longest heavy hex bolt you can supply?
16 inch (400 mm) length in 4 inch diameter from forged blank. Longer studs use stud bolt or threaded rod instead of head-and-shank bolt.
Q. Do you supply heavy hex nuts and washers from the same heat lot?
Yes. Matched-grade heavy hex nuts to ASME B18.2.2 and matched-grade washers to ASME B18.21.1 ship from the same Cr-Mo-V heat lot on call-out.
Related 21CrMoV5-7 Form Factors
Browse the full 21CrMoV5-7 form-factor range: Round Bar · Stud Bolts · Hex Bolts · Tap Studs · Body-Bound Studs · Anchor Bolts · U-Bolts · Threaded Rod · Nuts · Washers · Forgings. Back to the 21CrMoV5-7 Alloy Hub.
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