Hydraulic Shock and Sway Suppressors ( Hydraulic Snubbers )

Transcription

1 Hydraulic Shock and Sway Suppressors ( Hydraulic Snubbers )

2 Hydraulic shock- and sway suppressors Applications PSS hydraulic shock- and sway suppressors are used to prevent damage to appliances, pipework, pressure vessels, valves and pumps which might otherwise be caused by dynamic forces applied suddenly. These include dynamic loading occurring during operation (water hammer, pipe bursts or shocks caused by safety-valves blowing off), and on the other hand by external influences (earthquakes, explosions and wind loads). In addition, the PSS snubbers can be used as oscillation-dampers for oscillating pipework and plant components, provided the amplitude exceeds 0.5 mm. By using the snubbers the dynamic displacement is reduced to a minimum. Movements caused by temperature alteration are not obstructed by the snubbers. Function On imposition of a dynamic load moving the piston faster than the response velocity preset by PSS, the snubber valve closes and the snubber absorbs the force. The overflow valve or the bypass valve has the task of limiting the piston movement to the specified nominal loading. Construction features PSS snubbers can be installed in any desired position. The fluid level in the snubbers can be easily and reliably observed from the relative positions of the pistons rods. PSS snubbers are modular designed. Matching and alterations to suit requirements are very easy to accomplish. This is how special solutions can be offered so quickly, in accordance with the customer's requirements. The PSS snubber has two independently-operating pairs of valves, accessible externally. By this means the snubber can be optimised to the customer's requirements on the test-bench (response velocity, bypass velocity and reaction travel). Even after installation, adjustment is possible if required. Due to the independently-operating lock-up valves, the PSS snubbers also have adequate power when working in tension and compression directions at high frequency rates. When changing direction, the second valve can react before the first valve has returned to its starting position. The PSS snubbers have only very little frictional and starting resistances, because friction areas are very small. We placed a high priority on low friction when selecting the sealing materials. The initial pressure in the system required for tightness is very low. The seals are all made of high quality materials and have a very long service life.

3 When the PSS snubbers were designed, the following standards were taken into account: VGB - Power-Tech guideline R510L KTA - Nuclear Safety Standards Commission BS 3974, Part 1 ANSI B31.1 MSS SP 58 MSS SP 69 SVDB guidelines ASME Section III, Sub-section NF Models available PSS hydraulic snubbers are available as a standard model, and as a special model designed for low-temperature and offshore uses. Standard model - Housing parts coated with extremely corrosion-resistant zinc-iron coating µm. - piston rods coated all round with 40 µm electroless nickel and the shaft additionally coated with 20 µm of hard chrome. Special model - Housing parts of stainless steel and additionally galvanised with 15 µm nickel coating. - piston rods are made of chloride-resistant stainless steel with a 10 µm hard chrome coating on the shaft. Further material combinations and special coatings are available at the customer's request. Standard settings and test values at room temperature in accordance with KTA and VGB-R510L: Starting resistance: Frictional resistance: Response velocity: Bypass velocity: Piston rod travel Sa: Piston rod travel Sb: Temperature: Deflections: max 2 % of the nominal load (or 300 N for snubbers with a nom. load less or equal 15 kn) max 2 % of the nominal load (or 200 N for snubbers with a nom. load less or equal 10 kn) 3-6 mm/s mm/s > 0.5 mm (lost motion) < amount + / nominal travel (peak to peak) max. operating temperature 80 C (short-time operating temperature for a duration at max. 3 hours 150 C) max. deflection cross to the bolt axis: ± 70 max. deflection in the bolt axis: min. ± 5

4 with extension Option 0 Option 0 Option 1 Option 1 Option 2 Option 2 Option 3 Option 3 Fig. 200A, 200B, 202 Fig. 201A, 201B, 203 ( with extension ) Option 0:, Option 0:, 1 extension piece Option 1: 1 rear bracket EHS 14 S at the fixpoint Option 1: 1 rear bracket EHS 14 S at the fixpoint 1 extension piece Option 2: 2 rear brackets, EHS 14 S Option 2: 2 rear brackets, EHS 14 S 1 extension piece Option 3: 1 rear bracket EHS 14 S at the fixpoint 1 special dynamic pipe clamp Option 3: 1 rear bracket EHS 14 S at the fixpoint 1 extension piece 1 special dynamic pipe clamp

5 Allowable Loads Cylinder - bore Figure Figure 1 x F N 1,5 x F N 1,7 x F N size with Load case H* Load case HZ* Load case HS* (inches) extension A / B** Normal / Upset C** Emergency D** Faulted 1/4, 1/2, 1 200A 201A /2 200A,200B 201A,201B /2 200A,200B 201A,201B /4 200A,200B 201A,201B A 201A A 201A A 201A /2 202B B B B B /2 202B /2 202B /2 202B /2 202B B * = KTA Nuclear Safety Standards Commission ** = ASME Section III, Sub-section NF Technical Data Fig. 200A / 201A Fig. 200A / 201A C L 1 L 2 middle L 3 L 4 A B H ØD L 5 L 6 R F S K EHS Size N.load Stroke middle middle min. max. min. max. ±40 14 S kn mm mm Size 1 1 / 2 " ,0 106, B 2 1 / 2 " 3 1 / 4 " 4" , , , , , , , , , D 1 E 1 F 1 5" ,5 205, G " ,0 220, H special strokes on request

6 Technical Data Fig. 200B / 201B Fig. 200B S1 D D F R R L6 L1 middle L5 S Fig. 201B S1 F L2 middle L3 S Fig. 200B/201B L1 midd. L2 middle L3 ØD L5 L6 R F S S1 weight Size N.load Stroke min. min. max. min. max. kn inch mm mm kg 1 1/2" 13 5" 127, , , " 254, ,0 5" 127, ,5 2 1/2" 45 10" 254, , , " 381, ,7 20" 508, ,8 5" 127, ,1 3 1/4 " 78 10" 254, , , " 381, ,7 20" 508, ,3 special strokes on request

7 Technical Data Fig. 202 / 203 Fig. 202 / 203 C L 1 L 2 ±40 middle L 3 L 4 L5 L6 L7 A B H ØD R F ØD1 Size N.load Stroke middle middle min. max. min. max. ±40 kn mm mm 8,5" ,5 766,5 715,5 3081, ,5 893,5 842,5 3008, , , " ,5 856,5 821,5 3396, ,0 1047,0 948,5 3343, , , " ,5 876,5 870,5 3718, ,0 1067,0 997,5 3665, , , " ,5 966,5 945,5 4107, ,0 1157,0 1072,5 4054, , , sizes 17" up to 43" on request

8 PSS Pipe Support Systems GmbH International Geßbachstr. 2, D Neunkirchen our post office adress: Postfach 1142, D Neunkirchen Tel (0) Fax 0049 (0)