DP163 Pilot Operated Pressure Reducing Valve

1. Safety information

Safe operation of the DP163 can only be guaranteed when it is installed, commissioned, used and maintained by qualified personnel in compliance with these operating instructions. General installation and safety instructions for pipeline and plant construction, together with the correct use of tools and safety equipment, must also be followed.

1.1 Intended use

Using this guide, the name-plate and the Technical Information Sheet, check that the DP163 is suitable for the intended steam application. The product complies with the applicable EU Pressure Equipment Directive and UK Pressure Equipment (Safety) Regulations requirements and carries the required mark where applicable.

• Check material suitability, pressure, temperature and their maximum and minimum values.
• If the product limits are lower than those of the system, or if a malfunction could create dangerous overpressure or overtemperature, provide a safety device to prevent the limit being exceeded.
• Determine the correct installation situation and direction of fluid flow.
• The product is not intended to withstand external stresses induced by the system. The installer must assess these stresses and take precautions to minimise them.
• Remove protection covers from connections and protective film from name-plates before installation on steam or other high-temperature applications.

1.2–1.6 Access, lighting, pipeline contents, environment and the system

• Provide safe access and, where necessary, a guarded working platform before working on the product. Arrange suitable lifting gear where required.
• Provide adequate lighting, particularly for detailed or intricate work.
• Consider what is or has been in the pipeline, including flammable materials, substances hazardous to health and extreme temperatures.
• Assess explosion-risk areas, lack of oxygen, dangerous gases, hot surfaces, fire hazards, excessive noise and moving machinery around the product.
• Consider the effect of the proposed work on the complete system. Isolation of vents or protective devices, or disabling controls or alarms, can put personnel and equipment at risk. Open and close isolation valves gradually to avoid system shocks.

1.7–1.11 Pressure, temperature, tools, clothing and permits

• Isolate pressure and safely vent the system to atmospheric pressure. Consider double isolation, locking or labelling closed valves. Never assume that the system is depressurised just because a pressure gauge reads zero.
• Allow time for temperature to normalise after isolation to avoid burns.
• Have suitable tools and consumables available and use genuine Spirax Sarco replacement parts.
• Assess the need for protective clothing against chemicals, high or low temperature, noise, falling objects and eye or face hazards.
• All work must be carried out or supervised by a competent person. Follow any formal permit-to-work system; where none exists, a responsible person should know the work being done and arrange assistance where necessary. Post warning notices if required.

1.12–1.16 Handling, residual hazards, freezing, disposal and returns

• Assess manual handling risks for large or heavy products and use an appropriate lifting or handling method.
• The external surface may become very hot in normal service, and products may retain fluid because they are not self-draining. Take care when dismantling or removing the valve.
• Protect the product against frost damage where it can be exposed to below-freezing temperatures.
• Unless stated otherwise, the product is recyclable and no ecological hazard is anticipated when it is disposed of with due care.
• When returning a product, provide written information about contamination residues, mechanical damage and any associated hazards, including relevant safety data sheets.

Warning: If the DP163 is not used in the manner specified by these instructions, the protection provided may be impaired.

2. General product information

The DP163 is a pilot operated pressure reducing valve with a stainless steel body for steam applications. It is supplied with a pressure adjustment spring selected for the downstream pressure stated on the order. The spring is not pre-set.

For additional product data, use the DP163 Technical Information Sheet. Available sizes are DN15LC, DN15, DN20, DN25, DN32, DN40, DN50 and DN80. Standard flanges are EN 1092 PN25 and PN40, BS 10 Table J and ASME/ANSI 300; ASME/ANSI 150 and JIS 20 are available on request.

2.1 Pressure and temperature limits

The pressure-temperature curve and the ordered connection group must be checked together. Do not operate in a region marked as prohibited by the Technical Information Sheet.

3. Installation

3.1 Supply

The DP163 is supplied ready for fitting. The pressure adjustment spring is selected to suit the downstream pressure stated on the order, but it is not pre-set.

3.2 Fitting

Always fit the valve in horizontal pipework with the main diaphragm chamber below the line. For high capacities, widely varying loads or standby service, two or more valves may be installed in parallel.

3.3–3.7 Pipeline sizing, stress, isolation, drainage and dirt

• Size the pipework on both sides so that velocity does not exceed 30 m/s. A correctly sized valve is often smaller than the upstream pipework, while the downstream pipework is generally larger.
• Do not impose line stresses caused by expansion or inadequate support on the valve body.
• Use fullway isolation valves where possible.
• Drain the pipework adequately so that the valve receives dry steam. A separator in the steam supply is the ideal arrangement. If closing the downstream isolation valves could flood the downstream pipework, install a trap set to remove condensate from radiant losses.
• Protect the valve with a strainer the same size as the upstream pipework and fitted with a 100 mesh screen. Fit the strainer on its side to prevent water accumulating.

3.8 Pressure sensing

For closer control, improved stability or maximum capacity conditions, replace the balance pipe with an external pressure sensing pipe as follows:

1. Remove the balance pipe assembly.
2. Blank the resulting 1/8 inch BSP tapping in the side of the body with the plug supplied in the linen bag attached to the valve.
3. Blank the other 1/8 inch BSP tapping in the side of the pilot valve chamber with the plug fitted in the tapping on the front of the pilot valve chamber.
4. Fit the supplied brass compression fitting and compression ring into the pilot valve chamber tapping. It accepts 6 mm outside-diameter pipe. If suitable pipe is unavailable, remove the fitting and screw 1/4 inch nominal-bore steel pipe directly into the pilot valve chamber.
5. Connect the sensing pipe to the top of the reduced-pressure main at a point with at least 1 m or 15 pipe diameters of straight pipe, uninterrupted by fittings, in either direction, whichever is greater.
6. Arrange the sensing pipe with a positive fall so condensate drains away from the DP163. Where a fall cannot be maintained when entering the top of a large reduced-pressure main, connect the pressure control pipe into the side of the main.

3.9 Pressure gauges

A downstream pressure gauge is essential so that the valve can be set correctly. An upstream pressure gauge is an essential diagnostic tool.

3.10 Bypass

If a constant steam supply must be maintained while the reducing valve is serviced, install a bypass. The bypass valve will normally be the same size as the reducing valve. Padlock the handwheel to prevent unauthorised use and keep the bypass under constant manual supervision. The bypass may be above or beside the main assembly, never below it.

3.11 Safety valve

Fit a safety valve to protect downstream equipment from excessive pressure. Set it to lift below the safe working pressure of the downstream equipment. It will normally be sized to pass the full capacity of the reducing valve if the DP163 fails fully open. Account for the safety valve reseat characteristic and the no-load pressure setting: for a DIN safety valve with a typical 10% blowdown, the minimum possible set pressure equals the no-load set pressure plus the blowdown value plus a margin of at least 0.1 bar. Take discharge pipework to a safe place.

3.12 Position in relation to other control valves

• Install system isolation valves upstream of the DP163.
• Keep downstream fast-acting control equipment, such as pulsed piston actuated valves, at least 50 pipe diameters away. If that is impractical, use an intermediate vessel to reduce transmitted pressure pulses.
• Where both a downstream safety valve and a control valve are used, fit the safety valve downstream of the control valve rather than between the DP163 and the control valve. This reduces nuisance operation from slight leakage while protecting the downstream system.
• Trap intermediate downstream pipework properly so condensate does not build up on the downstream side.

4. Commissioning

4.1 Start-up and setting the valve

1. Ensure all connections are properly made and all valves are closed.
2. Turn the adjustment screw fully anticlockwise until the spring is slack.
3. Open the small valve in the pressure control line.
4. Blow through the approach pipework by removing the cap and screen from the strainer protecting the steam trap that drains the upstream pipework. Replace them afterwards. Do not remove the screen from the main line strainer during this operation. Inspect and clean the main line strainer at regular intervals when necessary.
5. Slowly open the upstream isolation valve until fully open.
6. Using a 19 mm A/F spanner, slowly turn the adjustment screw clockwise until the desired downstream pressure is shown.
7. Hold the adjustment screw with the spanner and tighten the lock-nut to secure the pressure setting, ensuring the C washer stays in position.
8. Slowly open the downstream valve until fully open.

4.2 Two or more valves in parallel

For parallel valves, it is advantageous to use two unequal sizes: choose the smaller valve for lower loads and bring the larger valve into operation for normal and maximum demand. Set each valve independently against dead-end conditions with a downstream isolation valve closed. Set the smaller valve approximately 0.1 bar higher than the larger valve.

5. Maintenance

Before any maintenance, follow the safety information in Section 1.

Warning: The body gasket contains a thin stainless steel support ring that may cause physical injury if it is handled or disposed of incorrectly.

Warning for DP163: The 316 stainless steel used in the product, particularly in screwed or close-fitting parts, is susceptible to galling or cold welding. Take great care during dismantling and reassembly. Where the application permits, apply a light smear of PTFE-based grease to mating parts before reassembly.

5.1 Routine maintenance

Dismantle the valve for a complete overhaul every 12 to 18 months, ideally with the valve removed from the line. Parts that may require replacement or refurbishment include the main valve and seat, pilot valve assembly, pilot diaphragms and main diaphragms. Clean the pushrod liner bush, control pipework, fittings and control orifices of scale deposits when necessary.

5.2 Diaphragms and cleaning

If diaphragms are not renewed, do not turn them over; refit each diaphragm in exactly the same position as when removed. Keep the control orifices in the control pipe adaptors and the balance pipe clear of dirt. Blow through with compressed air if necessary. Do not use a drill on control orifices, because enlarging them can upset operation.

5.3 Pressure adjustment springs and ranges

5.4 Renew or change the control spring

1. Release the lock-nut and turn the adjustment screw anticlockwise until the spring is slack.
2. Slide out the C washer from beneath the lock-nut and remove the cover.
3. Remove the old spring and replace it with the new spring, remembering the top spring plate.
4. Replace the cover and C washer. Turn the adjustment screw clockwise until the desired pressure is obtained.
5. Hold the adjustment screw and tighten the lock-nut, ensuring the C washer stays in position.

5.5 Renew the pilot valve assembly and bellows seal

1. Isolate the reducing valve and reduce pressure to zero.
2. Release the lock-nut and turn the adjustment screw anticlockwise until the spring is slack.
3. Slide out the C washer and remove the cover.
4. Remove the spring and top spring plate.
5. Undo the four M10 nuts and remove the spring housing, bottom spring plate and diaphragms.
6. Undo the pipework union nuts and release the 6 mm stainless steel pipework.
7. Undo the pilot valve housing nuts and remove the housing, ensuring that the main valve spring remains correctly positioned on the main valve head.
8. Unscrew the pilot valve assembly, including its integral strainer screen, with a 27 mm A/F socket and remove the plunger.
9. Unscrew the bellows seal assembly with a 24 mm A/F socket and replace it if necessary.
10. With the bellows seal removed, screw in the new pilot valve assembly and tighten to 115 N m.
11. Insert the plunger from the top and check for a 0.7 mm gap between the plunger top and a straight edge across the diaphragm recess. Machine the plunger if necessary to achieve the gap, then remove sharp edges.
12. Locate the bellows seal carefully over the plunger and tighten to 115 N m.
13. Press the top of the bellows lightly onto the plunger and check with the straight edge for a slight clearance.
14. Ensure gasket faces on the pilot valve block and body are clean, and the main valve spring is positioned correctly.
15. Fit a new gasket and secure the pilot valve block with the nuts, using the torque table below.
16. Refit the 6 mm stainless steel pipework and tighten union nuts for a steam-tight seal.
17. Refit both diaphragms in the same orientation as removed, with all contact surfaces clean.
18. Position the bottom spring plate and secure the spring housing with the four M10 nuts to 50 N m.
19. Replace the spring and top spring plate. Turn the adjustment screw until it just locates on the top spring plate, then replace the cover and C washer.
20. Return the valve to service by following the necessary steps in Section 4.1.

5.6 Clean the pilot valve strainer screen

1. Isolate the reducing valve and reduce pressure to zero.
2. Release the lock-nut and turn the adjustment screw anticlockwise until the spring is slack.
3. Undo the union nuts and release the 6 mm stainless steel pipework.
4. Undo the pilot valve housing nuts and remove the housing with the spring housing assembly. Ensure the main valve spring stays correctly positioned on the main valve head.
5. Hold the pilot valve block upside down and unscrew the screen retaining nut with a 27 mm A/F spanner.
6. Remove and clean the screen, taking care not to lose the small return spring and ball.
7. Refit the ball, spring, screen and retaining nut. Tighten the retaining nut to 15 N m.
8. Clean the gasket faces and ensure the main valve spring is positioned correctly.
9. Fit a new gasket and secure the pilot valve block using the torque table in Section 5.5.
10. Refit the 6 mm stainless steel pipework and tighten the union nuts for a steam-tight seal.
11. Return the valve to service using the necessary steps in Section 4.1.

5.7 Renew the pilot valve diaphragms

1. Isolate the reducing valve and reduce pressure to zero.
2. Release the lock-nut and slacken the spring fully with the adjustment screw.
3. Remove the C washer and cover.
4. Remove the spring and top spring plate.
5. Undo the four M10 nuts and remove the spring housing, bottom spring plate and old diaphragms.
6. Fit two new diaphragms with all contact faces clean.
7. Position the bottom spring plate and secure the spring housing with the four M10 nuts to 50 N m.
8. Replace the spring, top spring plate, cover and C washer.
9. Return the valve to service using the necessary steps in Section 4.1.

5.8 Renew the main diaphragms

1. Isolate the reducing valve and reduce pressure to zero.
2. Undo the long union nut and pull it away.
3. Undo the M12 nuts and bolts and lower the diaphragm chamber with the two stainless steel diaphragms, diaphragm plate and pushrod assembly.
4. Thoroughly clean the lower diaphragm chamber and contact surfaces.
5. Replace the diaphragm plate and pushrod assembly. Loosely refit the lower chamber on the bolts either side of the union and locate the spigot in the recess. Ensure the connecting stainless steel pipe is in its fitting.
6. Bring the two main diaphragms together and slide them into position, easing the diaphragm plate upwards to clear them.
7. Push the lower chamber home into its recess and refit the M12 nuts and bolts. Tighten to 75 N m.
8. Retighten the long union nut for a steam-tight seal.
9. Return the valve to service using the necessary steps in Section 4.1.

5.9 Service or renew the main valve and seat

1. Isolate the pressure reducing valve and reduce pressure to zero.
2. Undo the union nuts and release the 6 mm stainless steel pipework.
3. Undo the pilot valve housing nuts and remove the pilot valve block with the spring housing assembly.
4. Remove the main valve spring and main valve head.
5. Remove the main seat with the appropriate socket. A special tool is required for DN80.
6. Examine the seating faces. If wear is slight, lap the main valve head and seat on a flat plate with fine grinding paste.
7. If either part is badly worn or unfit, replace it. The seat and valve head are not supplied as matched pairs, so both do not necessarily need replacement.
8. Clean the thread and seating surface in the body, refit the seat and tighten to the torque table below.
9. After a part is fitted or extensive lapping is carried out, reset the main valve pushrod for the correct valve lift.
10. Expose the main diaphragm plate and pushrod assembly using the diaphragm renewal procedure.
11. Refit the pushrod assembly and main valve head, ensuring the head locates on the seat.
12. Open the main valve by pushing the plate against the body stop and check lift with a depth gauge.
13. If lift differs from the table, slacken the lock-nut and adjust the pushrod in or out of the diaphragm plate. Retighten the lock-nut when lift is correct.
14. Replace the lower valve assembly using the main diaphragm procedure.
15. Clean gasket faces, refit the main valve head and position the main valve spring correctly.
16. Fit a new gasket and secure the pilot valve block using the pilot-block torque table.
17. Refit the 6 mm stainless steel pipework, tighten union nuts and return the valve to service using Section 4.1.

6. Spare parts

Available DP163 spare categories include main diaphragms (two), pilot diaphragms (two), pilot valve seal assembly, pilot valve and plunger assembly, main valve assembly, main valve return spring, pressure adjustment spring, control pipe assembly, balance pipe assembly, body gasket, securing stud and nut sets, diaphragm chamber securing bolt and nut sets, and the pushrod and main diaphragm plate assembly.

For general maintenance, the maintenance kit is a standby set covering the available spares designated for kit inclusion. Order by stating the spare description, valve size, DP163 model number and pressure rating. Spare materials for the DP163 must not be assumed interchangeable with other valve bodies.

7. Fault finding

Before undertaking fault tracing, isolate the valve and ensure upstream and downstream pressures are zero.

7.1 Downstream pressure zero or too low

1. Check that high-pressure steam reaches the valve, the steam is turned on and the strainer is clear. An upstream pressure gauge assists commissioning and fault finding.
2. Check whether the pressure adjustment spring is broken.
3. Check for a blocked pipe assembly and blow through it after uncoupling the union nuts.
4. Check and clear a blocked control orifice.
5. Check for fractured main diaphragms and renew them using Section 5.8.
6. Check the pilot valve plunger length using the procedure in Section 5.5.
7. Check that the valve has sufficient capacity. Confirm upstream pressure, ensure the balance pipe is correctly arranged and fit an external pressure sensing pipe where required. If downstream pressure remains too low, a larger valve may be required.

7.2 Downstream pressure too high

1. Check the external pressure sensing pipe for blockage and blow through it after dismantling.
2. Check and clean a blocked control orifice.
3. Check and renew fractured pilot valve diaphragms.
4. Check for a sticking pilot valve or plunger and follow Section 5.5.
5. Check that the main valve seats correctly.
6. Check whether the main valve pushrod is sticking and follow the lift procedure.
7. Check the pilot valve plunger length.
8. Check that the pilot valve seats correctly.

7.3 Hunting

1. Check that upstream pressure is stable and that upstream pipework or strainers are not restricting flow.
2. With stable upstream pressure and correct sizing confirmed, set the valve against dead-end conditions and apply full load. Excessive downstream pressure drop indicates that the valve may be undersized.
3. Check whether the steam is excessively wet and compare the installation with the recommended arrangement.
4. Check that the external pressure sensing tapping is not in a turbulent area.
5. Check the pipe assembly for loose dirt and blow it through.
6. Check for a sticking pilot valve, pilot plunger or main valve pushrod.
7. Check whether pilot or main diaphragms have been overstretched and replace them where required.