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Brand: Spirax Sarco
Spirax Sarco SDP143 Pilot Operated Pressure Surplussing Valve
Description
Keeping upstream pressure down on steam and gas lines
The Spirax Sarco SDP143 is a cast steel, pilot operated pressure surplussing valve suitable for steam, air and industrial gases; the datasheet notes that it is not suitable for oxygen service. A surplussing valve opens to pass excess pressure from the system it protects, and the SDP143 controls by sensing the upstream pressure through a sensing pipe taken from a union on the valve.
It is available from DN15LC (low capacity version) through DN15, DN20, DN25, DN32, DN40 and DN50 to DN80, with flanges to EN 1092 PN40, BS 10 Table J, ANSI 300 and ANSI 150, and is supplied with certification to EN 10204 3.1 when requested at order.
Technical specifications
| Parameter | Specification |
|---|---|
| Model | Spirax Sarco SDP143 pilot operated pressure surplussing valve, cast steel body |
| Sizes | DN15LC, DN15, DN20, DN25, DN32, DN40, DN50, DN80 |
| End connections | Flanged EN 1092 PN40, BS 10 Table J, ANSI 300, ANSI 150 |
| Media | Steam, air and industrial gases; not suitable for oxygen |
| Adjustment springs | Red 0.2 to 17 bar g; grey 16 to 24 bar g |
| Body design | PN40; max. design pressure 26 bar g (ANSI 150: 17.2 bar g at 40 °C); max. design temperature 300 °C at 26 bar g |
| Max. upstream pressure, saturated steam | 26 bar g (ANSI 150: 14 bar g) |
| Max. differential pressure | 26 bar (ANSI 150: 14 bar) |
| Kv (full capacity) | 1.0 / 2.8 / 5.5 / 8.1 / 12.0 / 17.0 / 28.0 / 64.0 (DN15LC to DN80) |
| Test pressure | 60 bar g cold hydraulic; 40 bar g with internals fitted |
| Weight, approx. | 15 kg (DN15), 23 kg (DN25), 42 kg (DN50), 103 kg (DN80) |
| Certification | EN 10204 3.1 available; EU PED 2014/68/EU |
Setting ranges, pressure limits and standards
Two colour-coded pressure adjustment springs are listed: red for 0.2 to 17 bar g and grey for 16 to 24 bar g. The body design condition is PN40, with maximum design pressure limited to 26 bar g for EN 1092 PN40, ANSI 300 and BS 10 Table J flanges and to 17.2 bar g at 40 °C for ANSI 150. The maximum design temperature is 300 °C at 26 bar g and the minimum 0 °C. Maximum upstream pressure for saturated steam service is 26 bar g (14 bar g for ANSI 150) and maximum differential pressure is 26 bar (14 bar for ANSI 150).
The valve complies with the EU Pressure Equipment Directive 2014/68/EU and carries the CE mark when required. Hydraulic test pressure is 60 bar g cold, and with internals fitted it must not exceed 40 bar g. Certification and inspection requirements must be stated when the order is placed.
Sizing, capacity and installation
Full-lift Kv values for safety valve sizing are 1.0 (DN15LC), 2.8 (DN15), 5.5 (DN20), 8.1 (DN25), 12.0 (DN32), 17.0 (DN40), 28.0 (DN50) and 64.0 (DN80). Steam and compressed air capacity charts are used for selection; in the datasheet example a duty of 600 kg/h from 6 to 4 bar needs at least a DN32, and for superheated steam a correction factor of 0.95 applies at 55 °C of superheat and 0.9 at 100 °C.
The valve should be installed in a horizontal pipeline with the direction of flow shown by the arrow on the body. Dimension A is 130 mm for DN15 PN40, 160 mm for DN25 and 230 mm for DN50, with weights from about 15 kg (DN15) to 103 kg (DN80). For reducing rather than surplussing duty see the Spirax Sarco DP27, and browse more steam valves under Control Valves.
How the Spirax Sarco SDP143 works
The valve senses the pressure upstream through a small pipe taken from a union. A pilot valve compares this pressure with the spring setting. When the pressure rises above the setting, the pilot opens and moves the main valve open. The extra pressure passes out and the upstream pressure falls back to the set value.
Where the SDP143 is used
- Steam headers that need pressure relief to a lower line
- Process lines with surplus steam
- Compressed air systems
- Industrial gas lines
- Boiler house back pressure duties
Selection checklist for the SDP143
- Size from DN15LC to DN80
- Spring range, red or grey
- Upstream pressure to be held
- Differential pressure
- Flange standard
- Kv value for the flow
- Steam, air or gas
- Temperature of the medium
Installation, commissioning and maintenance notes for the SDP143
Fit the valve with the flow arrow along the pipe. Run the sensing pipe from the union to the upstream line. Fit a strainer upstream to protect the pilot. Set the spring while the system is under pressure. Check the setting at each service.
Requesting a quotation for the Spirax Sarco SDP143
Please send the size, the pressure setting, the flow and the flange type. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.
SDP143 sizes
The sizes are DN15LC, DN15, DN20, DN25, DN32, DN40, DN50 and DN80.
SDP143 spring ranges
The red spring covers 0.2 to 17 bar g and the grey spring covers 16 to 24 bar g.
SDP143 body design
The body is cast steel, designed for PN40.
SDP143 design pressure
The maximum design pressure is 26 bar g, and 17.2 bar g for ANSI 150 flanges.
SDP143 design temperature
The maximum design temperature is 300 degrees C at 26 bar g.
SDP143 flow capacity
The Kv values run from 1.0 for the DN15LC to 64.0 for the DN80.
SDP143 test pressure
The cold hydraulic test pressure is 60 bar g.
SDP143 weight
The weight is about 15 kg for DN15 and 103 kg for DN80.
Valve records for the SDP143
Record the spring setting, the upstream pressure and the date of each service.
Choosing the right SDP143 spring
Choose the spring so that the wanted set pressure falls in the middle of its range.
Documents and quotation
The technical information sheet TI-P004-01 is attached with materials, dimensions, spares and how to order. A typical order reads: one DN32 SDP143 with red spring and EN 1092 PN40 flanges. Please state the medium, upstream and set pressures, flow, connection standard and any certificate required.
Datasheets & Documents
- Datasheet Spirax Sarco SDP143 Pilot Operated Pressure Surplussing Valve Technical Information TI-P004-01 (Issue 8, manufacturer) Download
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About brand
Steam is the specialty of Spirax Sarco: how to generate it cleanly, distribute it, control it and get the condensate back. The company dates from 1888 and is based in Cheltenham, United Kingdom. Seven Star LLC lists Spirax Sarco clean steam equipment, bellows sealed stop valves, steam traps and steam flowmeters, and sources them for process plants, hospitals and food factories in Oman.
Spirax Sarco products listed here
The listing includes these main groups, along with further steam traps, pressure reducing valves and filters:
- Clean steam and hygienic equipment: the CSG-HS clean steam generator, STERI-TROL clean service control valve, SRV66 sanitary pressure reducing valve, SVL488 clean service safety valve and the BT6-B balanced pressure thermostatic steam trap
- Isolation valves: BSA and BSAT bellows sealed stop valves, the BSA3HP high pressure version, A3S and A3SS valves and the DBB3 double block and bleed valve
- Steam metering: ILVA variable area flowmeter and the TVA and TFA target flowmeters
The STS17.2 steam-trapping station is a compact assembly for drain points.
Where Spirax Sarco steam equipment is used
Plant steam systems in refineries, chemical plants, laundries and food production use Spirax Sarco steam traps, stop valves and flowmeters for distribution and energy accounting. Clean steam products serve sterilizers, bioreactors, pharmaceutical water systems and food contact processes, where stainless steel wetted parts and documented surface finish are required. Requests from the GCC are often for a like-for-like trap or valve on an existing line.
Ordering Spirax Sarco parts: what we need
Give the product type (for example BSA3T or BT6-B), nominal size, end connection and its standard (flanged PN or ASME class, screwed, butt weld or sanitary clamp), body material and the operating pressure and temperature. For steam traps add the condensate load and differential pressure. For Spirax Sarco flowmeters send line size, steam pressure and the flow range, plus the display or flow computer required. On clean steam items, state the surface finish and the material certificates you need. A nameplate photo helps where the type is not known.
Browse Spirax Sarco products by category: Clean Steam, Globe Valve, Flowmeters.
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Frequently Asked Questions
What does a surplussing valve do?
It opens to relieve excess upstream pressure; the SDP143 senses upstream pressure through a pipe taken from a union on the valve and controls it with a pilot.
Which sizes and flanges are available?
DN15LC and DN15 to DN80, flanged to EN 1092 PN40, BS 10 Table J, ANSI 300 and ANSI 150.
Is the SDP143 suitable for oxygen?
No. The datasheet states that it is not suitable for oxygen service; it is for steam, air and industrial gases.
What are the spring ranges?
Red 0.2 to 17 bar g and grey 16 to 24 bar g.
Is material certification available?
Yes, certification to EN 10204 3.1 is available if stated at the time of order.
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