Product Overview

Spirax Sarco BPT13 Maintenance Kit is a factory replacement capsule and seat assembly designed for BPT13 series brass balanced pressure thermostatic steam traps. It restores internal steam tightness and condensate discharge capabilities without detaching the trap body from the connecting pipework.

The kit supplies all primary internal wear parts: thermostatic capsule, conical spring, spacer plate, valve seat, seat gasket, internal strainer screen (for screened trap variants), and cap seals.

Key Features

• Inline renewal: internals replace directly through the top cap without breaking pipework connections.
• Three capsule fill options: standard STD (operates approximately 12 °C below saturation), sub-cooled SUB (operates approximately 24 °C below saturation), and near-to-steam NTS (operates approximately 4 °C below saturation).
• Stainless steel construction: capsule, spring (BS 2056 302 S26), spacer plate (BS 1449 304 S16), valve seat (BS 970 431 S29), and screen (ASTM A240 316L) resist steam erosion.
• Comprehensive cap sealing: kit includes two O-ring sizes in synthetic high-fluorine fluorocarbon for current trap bodies and accommodates flat gaskets on legacy models.
• Conical spring alignment: narrow end points downward to maintain central contact and downward force on the capsule.

Technical Specifications

Specification Parameter	Value / Range
Compatible Host Steam Traps	BPT13A, BPT13AX, BPT13S, BPT13SX, BPT13UA, BPT13UAX, BPT13US, BPT13USX
Trap Sizes Supported	3/8”, 1/2”, 3/4”
Maximum Operating Pressure (PMO)	13 bar g @ 220 °C
Maximum Operating Temperature (TMO)	250 °C @ 7 bar g (225 °C @ 7 bar g in Chinese documentation)
Maximum Allowable Pressure (PMA)	16 bar g @ 120 °C
Maximum Allowable Temperature (TMA)	250 °C @ 7 bar g
Minimum Allowable Temperature	-20 °C (minimum operating temperature 0 °C)
Cold Hydraulic Test Pressure	24 bar g
STD Capsule Discharge Temperature	Approximately 12 °C (53 °F) below steam saturation temperature
SUB Capsule Discharge Temperature	Approximately 24 °C (75 °F) below steam saturation temperature (earlier mark: ‘F’)
NTS Capsule Discharge Temperature	Approximately 4 °C (7 °F) below steam saturation temperature (earlier mark: ‘G’)
Fluorocarbon O-Ring Thermal Limit	315 °C (decomposition into hydrofluoric acid occurs above this temperature)

Component Parts and Materials

Item No.	Part	Material	Material Standard
3	‘O’ ring	Synthetic rubber high fluorine fluorocarbon	-
4	Capsule	Stainless steel	-
5	Spring	Stainless steel	BS 2056 302 S26
6	Spacer plate	Stainless steel	BS 1449 304 S16
7	Valve seat	Stainless steel	BS 970 431 S29
8	Valve seat gasket	Stainless steel	BS 1449 304 S11
9	Strainer screen	Stainless steel	ASTM A240 316L

Applications

• General steam main drainage, heating equipment, and tracing line condensate discharge using the STD capsule fill.
• Hospital sterilisers and wet steaming ovens requiring immediate condensate evacuation near saturation temperature with the NTS capsule fill.
• Vacuum return lines taking advantage of sub-cooled condensate discharge to avoid re-evaporation using the SUB capsule fill.
• Routine in-service overhaul and seating face renewal across Spirax Sarco BPT13 angled, straight, and union-connected steam traps.

Installation and Maintenance

1. Isolate the steam trap from both the supply line and return line, safely vent pressure to atmospheric, and allow the body to cool.
2. Unscrew the cap (2) using a 50 A/F spanner.
3. Lift out the conical spring (5), capsule (4), and spacer plate (6).
4. Unscrew the valve seat (7) using a 17 A/F spanner.
5. Remove the strainer screen (9) (if fitted) and the valve seat gasket (8).
6. Clean or replace the strainer screen (9) and place a new seat gasket (8).
7. Apply a thin film of anti-seize compound to the valve seat threads, screw in the new valve seat (7), and torque to 35 - 40 N m (26 - 29 lbf ft).
8. Insert the new spacer plate (6) centered over the valve seat (7); orient early unidirectional plates with highest points upward.
9. Position the new capsule (4) and conical spring (5) with the narrow end facing downward in contact with the capsule.
10. Fit the appropriate replacement O-ring (3) from the package into the cap groove (or fit a new flat gasket for older models) and tighten the cap (2).

Recommended Tightening Torques

Item	Part	Sealing Type	Tool Size	Torque (N m)	Torque (lbf ft)
2	Cap	‘O’ ring	50 A/F	50 - 60	37 - 44
2	Cap	Flat gasket	50 A/F	90 - 110	66 - 81
7	Valve seat	-	17 A/F	35 - 40	26 - 29