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Valves for Hot Oil (Thermal Heat Transfer Fluid) Service

Hot oil or thermal fluid is used as a heat transfer medium in indirect heating systems - circulated through heaters and heat exchangers to transfer heat without generating steam. Common fluids: Therminol VP-1, Dowtherm A, Marlotherm SH, Mobiltherm 605. Operating temperatures reach 300–400°C at relatively low gauge pressure (1–10 bar).

Pressure Range

1–15 bar (circulation system pressure)

Temperature

150–400°C (design temperature drives alloy steel selection above 370°C)

Industries

Chemical plant indirect heating, Textile processing, Food processing (frying, drying)

INDICATIVE ONLY - Reference DisclaimerHot oil is a high-temperature fire hazard. All equipment must comply with ATEX requirements where applicable, and all hot surfaces near valve packing or flanges must be insulated or shielded. System design should include automatic isolation on fire detection. Vajra Industrial Solutions accepts no liability for material selection decisions based on this guide.

What valves are used for Hot Oil (Thermal Heat Transfer Fluid) service?

Gate Valve (OS&Y, cast steel, metal seated) are recommended for Hot Oil (Thermal Heat Transfer Fluid) service: Standard isolation for hot oil mainline - low pressure drop, suitable to 400°C..

Key Properties - Hot Oil (Thermal Heat Transfer Fluid)

  • Operating temperature: 150–400°C at 1–10 bar gauge
  • Thermally stable synthetic or mineral oil base
  • Low vapour pressure at operating temperature - low pressure despite high temperature
  • Degrades over time - TAN (Total Acid Number) and viscosity must be monitored
  • Flash point typically 150–200°C - fire hazard if leaked onto hot surfaces

Vajra Industrial Solutions manufactures and supplies valves for Hot Oil (Thermal Heat Transfer Fluid) service — including gate valve (os&y, cast steel, metal seated) — in corrosion-appropriate materials selected for the operating conditions described here, with full material and test documentation.

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Material Compatibility - Hot Oil (Thermal Heat Transfer Fluid)

Ratings are indicative. Actual compatibility depends on concentration, temperature, velocity, and presence of contaminants. Always consult corrosion tables or a materials engineer.

MaterialRatingNotes
Carbon Steel (WCB/A105)ExcellentStandard material for all hot oil service up to 400°C at Class 150–300.
SS 316ExcellentAcceptable but not normally required unless process contamination is a concern.
A217 WC6 (1¼Cr-½Mo)ExcellentRequired above 370°C for long-term creep resistance per ASME B16.34.
PTFE seatsNot RecommendedPTFE has a 200°C maximum - metal seats required for hot oil above 200°C.
Cast IronPoorNot recommended - brittle at thermal cycling; use carbon or alloy steel.

Recommended Valves

Gate Valve (OS&Y, cast steel, metal seated)

Standard isolation for hot oil mainline - low pressure drop, suitable to 400°C.

Full selection guide

Globe Valve (cast steel, metal seated)

Flow control and modulating service on hot oil supply to heat exchangers.

Full selection guide

Ball Valve (trunnion, metal seated, extended stem)

Fast isolation with fire-safe capability and low-emission graphite packing.

Full selection guide

Check Valve (swing or tilting disc, cast steel)

Pump discharge non-return on hot oil circulation pumps.

Full selection guide

Valves to Avoid

PTFE-seated ball valves (temperature limit exceeded)

Cast iron body valves (thermal shock and brittleness risk at high temperature)

Plastic or elastomer-sealed valves

Standard ANSI 150 flanged connections above 370°C (check P-T ratings - A216 WCB limits)

Special Considerations

Thermal expansion - hot oil systems experience significant pipe expansion; flexible connections near valves
Fire risk: hot oil leaked onto surfaces above its autoignition temperature can self-ignite - fire-safe valves required
Graphite packing mandatory above 200°C - PTFE packing will fail
Thermal cycling: valve bodies should be specified for the full temperature range including cold start

Applicable Standards

ASME B16.34API 600 (cast steel gate/globe)ASME B31.3 (process piping)

Shop Valves for Hot Oil (Thermal Heat Transfer Fluid) Service

Other Fluid Services

Part of the Vajra Fluid Service Library

Hot Oil (Thermal Heat Transfer Fluid) Service — Procurement & Specification

Typical Applications

Chemical plant indirect heatingTextile processingFood processing (frying, drying)Pharmaceutical synthesisPlastics and rubber mouldingBitumen and asphalt plants

Available Standards

ASME B16.34API 600 (cast steel gate/globe)ASME B31.3 (process piping)

Material Options

Carbon Steel (WCB/A105)SS 316A217 WC6 (1¼Cr-½Mo)

Documentation Available

  • -EN 10204 3.1 Material Test Certificates (heat traceable)
  • -API 598 hydrostatic shell & seat test reports
  • -Dimensional inspection reports
  • -Full Manufacturing Data Record (MDR) / data book on request
View documentation package

Inspection Options

  • -In-house QC inspection on every order
  • -Third-party inspection (SGS / Bureau Veritas / TÜV / DNV) coordination
  • -Witness and hold points accommodated on request
View inspection & testing

Order Quantities

Flexible — from single critical-spare valves to full project lots.

Export

Worldwide export with complete documentation (COO, EUR.1, packing lists) to 20+ countries.

Custom Engineering

Built to your specification — materials, trim, pressure class and special service (NACE, fire-safe, IBR, cryogenic).

Delivery Support

Dispatch from Vadodara, Gujarat with documented lead times and priority handling for urgent requirements.

Engineering references

Reviewed by Process Engineering, Vajra Industrial SolutionsDiscipline: Process & Fluid Service EngineeringLast reviewed: 20 June 2026

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