Nord stone

Expansion Tank(CHW/Hot Water) – ASME – ASME Pressurized Utility Vessels

Expansion Tank

Introduction

Expansion Tanks (CHW/Hot Water) are ASME-certified pressurized utility vessels designed to accommodate thermal expansion in closed-loop heating or chilled water systems. These tanks maintain system pressure, prevent overpressure, and protect pumps, boilers, chillers, and piping networks.

At NORDSTONE., we manufacture robust expansion tanks with precise pressure control, engineered according to ASME Section VIII Div.1, PED, and NB certification.

What is an Expansion Tank?

In closed-loop hot or chilled water systems, water expands as temperature increases. Expansion tanks absorb this additional volume, preventing excessive pressure buildup. Key components include:

  • Cylindrical pressure vessel with skirt, leg, or saddle support
  • Inlet/outlet connections for system integration
  • Internal bladder or diaphragm (optional)
  • Air vent or pressure regulation valve
  • Drain connection for maintenance
  • Pressure gauge & safety relief valve port

Technical Features

1) Design & Construction:
  • Design Codes: ASME Sec VIII Div.1 / API / PED / NB
  • Tank Types:
    • Bladder/diaphragm expansion tanks
    • Open-type expansion tanks
    • Pressurized expansion tanks
    • Hot water expansion tanks
    • Chilled water (CHW) expansion tanks
    • Custom industrial expansion tanks
  • Design Pressure: 6 to 20 bar (higher on request)
  • Design Temperature: 5°C to 120°C (or project-specific)
  • Material Grade:
    • Carbon Steel: SA516 Gr.60/70, SA106 Gr.B
    • Stainless Steel: SS304/304L, SS316/316L
    • Duplex / Super Duplex SS
    • Internal linings/coatings for corrosion resistance
  • Internal Components:
    • Optional bladder or diaphragm
    • Air chamber & venting arrangement
    • Pressure safety connections
2) Capacity Range:

Expansion tanks are available from 50 Litres to 50,000 Litres, with fully custom volumes for industrial HVAC and hot/chilled water systems.

Typical Design Envelope

Parameter Range Remarks
Diameter 0.3 m – 3 m Customizable
Height 1 m – 6 m Project-specific
Volume 50 L – 50,000 L Larger units on request
3) Nozzle & Accessories:

Each expansion tank includes the following connections:

  • • Inlet/Outlet nozzles for system connection
  • • Safety relief valve port
  • • Pressure gauge connection
  • • Air vent valve (for pressurization)
  • • Drain connection for flushing
  • • Optional manway (for large tanks)
4) Surface Finish:
  • • SA 2.5 external sand/grit blasting
  • • Anti-corrosive primer coating
  • • PU / Epoxy top coat (custom colors available)
  • • Optional internal lining for aggressive fluids
  • • External insulation support options
Functional Advantages:
  • •

    Pressure Stability

    Absorbs water expansion and prevents overpressure in heating or chilled water loops.

  • •

    Equipment Protection

    Protects pumps, boilers, chillers, and piping against stress and water hammer.

  • •

    Extended System Life

    Reduces mechanical fatigue and maintains system equilibrium under temperature variations.

Optional Packages:
  • •

    Skid-Mounted Systems

    • ✔ Pre-charged nitrogen units
    • ✔ Pressure control instrumentation
    • ✔ Isolation valves & fittings
  • • Bladder/diaphragm replacement kits
  • • Custom nozzle & manway arrangements
  • • Coating & insulation packages
  • • Third-party inspection (TUV, DNV, BV, SGS)
Quality Assurance:

Each expansion tank undergoes the following QA/QC checks:

  • • Hydrostatic & pneumatic testing
  • • Ultrasonic testing (UT) for weld integrity
  • • Dye penetrant (DP) & magnetic particle testing (MPI)
  • • Material traceability (MTC – EN 10204 3.1)
  • • ASME U-stamp & NB certification (optional)
  • • Third-party inspection (TUV, BV, Lloyds, DNV, SGS)

Industries Served

  • • HVAC & Chilled Water Systems
  • • Hot Water & Boiler Systems
  • • Industrial & Utility Water Systems

Why Choose NORDSTONE.?

  • • 20+ years of expertise in pressurized utility vessels
  • • Advanced thermal, hydraulic & mechanical simulation
  • • ASME-certified manufacturing
  • • Customized expansion tank solutions for CHW/Hot water systems
  • • Full QA/QC, TPI & documentation support
  • • Proven reliability across industrial & commercial sectors
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Ready to Discuss Your Expansion Tank(CHW/Hot Water) – ASME Requirements?

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