Product Overview

Spirax Sarco BSA2 is an SG iron bellows sealed in-line stop valve engineered for isolation and throttling across industrial utility networks. Installed on steam, condensate, liquid, gas, and compressed air systems, it eliminates fugitive stem emissions to conserve thermal energy and maintain pipeline integrity.

Manufactured from EN-GJS-400-18-LT (5.3103) SG iron for both body and bonnet, the BSA2 model envelope encompasses standard flat disc isolation valves, BSA2T throttling plug configurations with stroke limiting hardware, and BSA2-BD (BSA2B/D) balancing disc valves for applications with elevated differential pressures. Pipeline connections conform to flanged EN 1092 / ISO 7005 PN16 and PN25 ratings with face-to-face dimensions to EN 558.

Key Features

• Ductile iron construction: body and bonnet cast in SG iron EN-GJS-400-18-LT (5.3103) rated up to 25 bar g design pressure and 350 °C maximum allowable temperature.
• Hermetic stem sealing: stainless steel bellows unit (WS 1.4571) isolates line fluid from the atmosphere, supported by graphite secondary stem packing.
• Tight shut-off performance: disc-to-seat shut-off complies with EN 12266-1 Rate A leakage standards.
• Throttling option compatibility: BSA2T version integrates a contoured throttling plug, stem locking screw, and handwheel nut tapped for an external stroke limiting bolt.
• Balancing disc configuration: BSA2-BD provides a two-stage pre-lifting pilot plug assembly for high differential pressure closure above size DN125.
• Soft seating insert option: optional R-PTFE (25% carbon filled) soft disc insert available from DN15 to DN100 for bubble-tight shut-off up to 230 °C.
• Certification: EN 10204 3.1 material and inspection certification available when specified at the time of order placement.

Technical Specifications

Specification Parameter	BSA2 / BSA2T PN16	BSA2 / BSA2T PN25
Body & Bonnet Material	SG iron EN-GJS-400-18-LT (5.3103)	SG iron EN-GJS-400-18-LT (5.3103)
Seat Material	Stainless steel AISI 420	Stainless steel AISI 420
Disc Material	Stainless steel DIN 17440 X30 Cr13	Stainless steel DIN 17440 X30 Cr13
Optional Soft Seat Insert	R-PTFE (25% carbon filled, DN15-DN100)	R-PTFE (25% carbon filled, DN15-DN100)
Bellows Material	Stainless steel WS 1.4571	Stainless steel WS 1.4571
Stem Material	Stainless steel AISI 420	Stainless steel AISI 420
Body/Bonnet Gasket	Graphite laminated with stainless steel insert	Graphite laminated with stainless steel insert
Nominal Size Range	DN15 to DN200	DN15 to DN250
Flange Standard	EN 1092 / ISO 7005 PN16	EN 1092 / ISO 7005 PN25
Face-to-Face Standard	EN 558	EN 558
PMA (Maximum Allowable Pressure)	16 bar g	25 bar g
TMA (Maximum Allowable Temperature)	350 °C	350 °C
PMO (Max Operating Pressure, Sat. Steam)	14.7 bar g	22.3 bar g
TMO Metal Seat	350 °C	350 °C
TMO Soft Seat (R-PTFE)	230 °C	230 °C
Minimum Operating Temperature	-10 °C	-10 °C
Cold Hydraulic Test Pressure	24 bar g	38 bar g
Leakage Standard	EN 12266-1 Rate A / ISO 5208 Rate A	EN 12266-1 Rate A / ISO 5208 Rate A

Applications

• Saturated steam distribution manifolds and terminal branch line isolation
• Condensate return systems and pumped condensate collection mains
• Industrial hot water and district heating circuits
• Compressed air supply networks and gas distribution lines
• Utility installations governed by European Pressure Equipment Directive 2014/68/EU Group 2 fluids

Dimensions and Physical Properties

Size	Face-to-Face A (mm)	Height B (mm)	Handwheel C (mm)	Weight (kg)
DN15	130	205	125	4
DN20	150	205	125	4
DN25	160	217	125	5
DN32	180	217	125	7
DN40	200	243	200	10
DN50	230	243	200	12
DN65	290	263	200	16
DN80	310	287	200	21
DN100	350	383	315	36
DN125	400	416	315	52
DN150	480	450	400	75
DN200	600	622	500	145
DN250 (PN25 only)	730	763	500	180

Full-open flow coefficients (Kv values) for standard BSA2 valves:

• DN15: 4 m³/h
• DN20: 7 m³/h
• DN25: 12 m³/h
• DN32: 19 m³/h
• DN40: 30 m³/h
• DN50: 47 m³/h
• DN65: 77 m³/h
• DN80: 120 m³/h
• DN100: 193 m³/h
• DN125: 288 m³/h
• DN150: 410 m³/h
• DN200: 725 m³/h
• DN250: 1145 m³/h

Throttling Control and Flow Characteristics (BSA2T)

BSA2T configurations are fitted with a profiled throttling plug to provide proportional flow control across handwheel rotations. Once set, the locking screw is tightened down to suppress vibration.

The handwheel nut features a threaded provision for fitting a stroke limiter bolt:

• DN15 - DN80: M8 x 50 mm hexagon bolt
• DN100 - DN150: M12 x 75 mm hexagon bolt
• DN200 - DN250: M12 x 100 mm hexagon bolt

Maximum permissible differential pressure in throttling duty:

• DN15 - DN80: 2.0 bar (29.00 psi)
• DN100 - DN125: 1.5 bar (21.75 psi)
• DN150: 1.0 bar (14.50 psi)
• DN200 - DN250: 0.8 bar (11.60 psi)

Kv values according to handwheel turns (water at 20 °C to EN 60534-2-3):

Handwheel Rotations	DN15	DN20	DN25	DN32	DN40	DN50	DN65	DN80	DN100	DN125	DN150	DN200	DN250
0	0	0	0	0	0	0	0	0	0	0	0	0	0
0.5	1.2	1.2	1.4	2.2	4.4	4.1	5.6	10.4	12.0	21	28	66	110
1.0	1.7	1.7	2.0	3.7	5.0	5.0	7.0	11.5	14.3	23	30	81	140
1.5	2.7	2.9	2.9	5.0	5.5	6.0	9.2	13.6	24.5	26	33	97	150
2.0	3.6	4.0	4.6	7.9	7.6	7.2	11.6	16.3	34.1	42	46	111	165
2.5	4.4	5.3	6.4	10.6	11.0	9.7	12.4	18.5	59.6	67	65	149	190
3.0	5.4	6.6	8.5	13.8	14.7	14.1	13.0	21.1	86.2	94	90	199	225
4.0	-	-	10.6	17.0	22.6	24.4	25.2	24.5	123.0	140	152	302	330
5.0	-	-	11.9	19.6	27.2	37.0	43.6	39.1	164.1	185	216	403	460
6.0	-	-	-	-	28.9	46.2	60.2	61.0	179.0	220	264	455	600
7.0	-	-	-	-	-	-	65.9	78.0	-	241	305	495	678
8.0	-	-	-	-	-	-	71.2	90.0	-	259	337	507	738
9.5	-	-	-	-	-	-	-	99.0	-	-	369	-	793
10.7	-	-	-	-	-	-	-	-	-	-	-	-	827

High Differential Pressure Balancing Disc (BSA2-BD)

When line differential pressures exceed specified limits on larger valves, manual shut-off against flow becomes impossible without pilot assistance. BSA2-BD valves incorporate a two-stage internal mechanism comprising a pre-lifting pilot plug (A) and a main disc (B).

Balancing discs are required when system differential pressure exceeds:

• DN125: > 25 bar ΔP
• DN150: > 17 bar ΔP
• DN200: > 10 bar ΔP
• DN250: > 6 bar ΔP (BSA2 only)

Installation requirement: On BSA2-BD valves, the flow direction must be reversed compared to standard stop valves. Upstream medium must enter on the bellows side into the upper valve chamber so that fluid pressure acts on top of the balancing disc to assist positive seating. If upgrading an existing BSA2 in-line, the valve body must be rotated 180° in the pipeline and clearly re-marked with a new flow direction arrow.

Maintenance, Bolting Torques and Spare Parts

All internal components of the BSA2 can be replaced in-line without removing the body from the pipeline. System pressure must be completely vented to atmospheric pressure and the assembly allowed to cool before loosening fasteners.

Recommended bonnet stud tightening torques for BSA2 and BSA2T (PN16 and PN25):

• DN15 - DN32 (17 mm A/F): 35 - 40 N m (26 - 29 lbf ft)
• DN40 - DN65 (19 mm A/F): 55 - 60 N m (40 - 44 lbf ft)
• DN80 - DN150 (24 mm A/F): 130 - 140 N m (95 - 103 lbf ft)
• DN200 (30 mm A/F): 260 - 280 N m (191 - 206 lbf ft)
• DN250 (36 mm A/F): 480 - 520 N m (352 - 382 lbf ft)

Handwheel retention torques:

• DN40 - DN80: handwheel nut has a left-handed thread; tighten anticlockwise to 40 N m (29 lbf ft).
• DN100 - DN250: apply Loctite 638 to handwheel boss threads and torque to 50 N m (36 lbf ft); tighten the left-handed handwheel nut anticlockwise to 40 N m (29 lbf ft).

Available spare part kits:

• Body/bonnet gasket and stem packing kit: includes body gasket (10b), bellows collar gasket (10a), and stem graphite packing ring (8).
• Stem and bellows assembly kit: includes stem and bellows assembly (6, 5), gaskets (10a, 10b), and packing ring (8).
• Disc kit: includes disc (4), replacement stem pin or collet/retaining hardware, gaskets (10a, 10b), and packing ring (8).
• Replacement handwheel (7).