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 Heat Exchanger Bolts (EN 10269 / 1.7709)
21CrMoV5-7 heat exchanger bolts are specified into channel-head bolting, shell-side flange bolting, and floating-head bolting on refinery, petrochem and gas-processing shell-and-tube heat exchangers. The Cr-Mo-V Q+T chemistry covers the temperature window for process-side service from 200 to 550 deg C where TEMA-style exchangers handle hydrocarbon streams.
Service Envelope
| Exchanger position | Typical metal temp | 21CrMoV5-7 use |
|---|---|---|
| Channel-head studs (cold service) | 50 to 200 deg C | Optional; 42CrMo4 acceptable |
| Channel-head studs (process) | 200 to 500 deg C | Primary choice |
| Shell-side flange bolting | 200 to 540 deg C | Primary choice |
| Floating-head bolting | 200 to 540 deg C | Primary choice |
| Tubesheet anchor bolts | 200 to 540 deg C | Primary choice |
Bolting Form Factors Used
- Stud Bolts: channel-head and shell-side flange bolting (the dominant heat-exchanger fastener)
- Heavy Hex Bolts: floating-head and inspection-port bolting
- Heavy hex nuts to ASME B18.2.2 in matched grade
- Hardened washers to ASME B18.21.1 in matched grade
Mechanical Floors for Heat Exchanger 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 heat-exchanger bolting to EN 10269. Cross-procurement on TEMA-design exchangers (US ASME spec) uses ASTM A193 Grade B16 dual-certified. API 660 heat-exchanger work uses ASTM A193 B16 with API supplementary requirements.
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. Which heat-exchanger types use 21CrMoV5-7 bolting?
Shell-and-tube exchangers in refinery (crude-distillation pre-heater train, hydrocracker effluent), petrochem (ethylene cracker quench tower, methanol synthesis loop), gas-processing (amine reboiler, glycol regenerator) and selected fired-heater inter-cooler bolting where process-side temperature reaches the 21CrMoV5-7 envelope.
Q. Is TEMA-style channel-head bolting always 21CrMoV5-7?
No. For cold-service exchangers (below 200 deg C process temperature) the cheaper 42CrMo4 or AISI 4140 grade is acceptable. 21CrMoV5-7 is the choice when process metal temperature exceeds 200 deg C and creep relaxation becomes a design concern.
Q. Do you supply matched-grade nuts and washers for TEMA exchangers?
Yes. Matched-grade heavy hex nuts to ASME B18.2.2 and hardened washers to ASME B18.21.1 from the same heat lot. Standard practice on TEMA-style and API 660 exchanger procurement.
Q. Are 21CrMoV5-7 bolts NACE-trim?
No. NACE MR0175 sour-service applications use ASTM A193 Grade B7M (Cr-Mo low-hardness, no V) per NACE acceptance criteria. 21CrMoV5-7 exceeds the NACE 22 HRC hardness cap and is not NACE-acceptable for direct contact with H2S-bearing streams.
Related Applications
More 21CrMoV5-7 service applications: Steam Turbine Bolts · Gas Turbine Bolts · Power Plant Bolting · Pressure Vessel Bolts · Boiler Bolts · Fired Heater Bolts · Petrochem Reactor Bolts. Back to the 21CrMoV5-7 Alloy Hub.
Satisfaction Survey
