IBR Certified Valves for Indian Boiler Circuits — Metallurgy and Selection

Technical guide · Supreme Valves India · Updated 2026-09-19

This guide covers engineering selection for valves on Indian boiler steam and feedwater circuits that fall under IBR scope: body metallurgy, trim, valve type by duty, steam quality effects, and common failure modes. Documentation, forms, and inspection sequencing are covered separately in IBR approved valves for Indian boiler circuits. Use both articles together when preparing a line list.

Steam circuit duties and valve types

Boiler associated piping is not one service. Map each tag to a duty before selecting type:

• Main steam isolation — Full-bore WCB gate valve (API 600), OS&Y, often flexible wedge. See API 600 steam isolation guide.
• Regulated flow, warm-up bypass, drains, vents — WCB globe valve. Do not throttle on a gate.
• Utility steam isolation where quarter-turn is preferred — WCB ball valve with seats rated for the steam temperature; confirm polymer limits carefully.
• Pump discharge and reverse-flow protection — WCB swing check or other NRV types sized for slam and minimum flow.
• Wet steam quality — Moisture separator upstream of turbines, PRVs, and sensitive instrumentation.

Selection criteria (metallurgy first)

ASTM A216 Grade WCB is the default cast carbon-steel body for matching carbon-steel steam pipe on saturated and many superheated duties within its ASME B16.34 temperature envelope. Full chemistry, P–T behaviour, and limits versus stainless grades are in the ASTM A216 WCB complete valve body material guide.

• Confirm design temperature against WCB group ratings — carbon steel derates as temperature rises.
• Use the pressure class selector only as a first pass; lock class to the piping specification.
• Feedwater and condensate may still use WCB, but check oxygen, pH, and copper content against plant chemistry rules.
• Alloy steel (for example WC6 / WC9 families) appears on higher-temperature superheated circuits — do not assume WCB is universal.
• Soft-seated ball valves: seat polymer often limits temperature before the WCB body does.

Standards for product design and test

IBR governs boiler regulatory acceptance. Product design still follows API/ASME practice:

• Pressure–temperature: ASME B16.34
• Gate: API 600; small forged: API 602
• Ball: API 608
• Check: API 594 / project-specified swing or dual-plate standards
• Testing: API 598 shell and seat; NDE of castings when the ITP requires it

Hydro test pressure must be consistent with the class and material group. Seat leakage criteria differ for metal-seated steam gates versus soft-seated utility balls — state the acceptance class on the datasheet.

Trim and hardfacing for steam

13Cr trim is common on WCB steam gates and globes. Hardfaced seating surfaces resist wire drawing where velocity across the seat is high — typical on globe control edges and on gates that have been misused for throttling. Stem material should resist packing corrosion under condensate. Graphite packing is typical for steam; verify emission and temperature requirements on the project packing specification.

Wet steam carries condensate droplets that erode seats and downstream fittings. Separators, steam traps, and correct line sloping reduce droplet impact. Specifying harder trim alone does not fix a chronically wet line.

Failure modes on boiler circuits

• Wire drawing on gates — Partial opening for “control” destroys seats; replace the duty with a globe.
• Thermal binding — Rapid heat-up of large gates without bypass warm-up.
• Seat erosion from wet steam — Inadequate drainage or missing separator.
• Check-valve slam — Undersized or wrong NRV type on pump discharge; see check valve / NRV types guide.
• Soft-seat failure on steam balls — PTFE used above its continuous temperature rating.
• External CUI — Carbon-steel bodies under wet insulation outdoors.
• Wrong alloy for high superheat — WCB specified where alloy steel is required by the piping class.

Installation and layout notes

Orient OS&Y stems for packing access. Provide warm-up bypass globes on large steam gates. Support actuators so stem alignment is preserved. Keep check valves the required number of diameters from pump discharges per manufacturer guidance. Place moisture separators where steam quality must be protected, with drains piped to safe collection.

Torque and actuator sizing for motorised isolation: calculators index.

RFQ checklist (selection-focused)

• Service: sat steam / superheat / feedwater / blowdown / condensate
• Design P and T; ASME class
• Valve type by duty (gate / globe / ball / check)
• Body grade (WCB or alloy) and trim / hardfacing
• Seat type for ball valves; confirm polymer temperature
• Ends, operator, tagging
• IBR documentation required — yes/no (details in the documentation guide)
• Steam quality devices (separator, traps) if part of supply scope

Structure the enquiry with the IBR valve checklist. Hub: IBR valves.

FAQ