Hydraulic Snubbers

Most hydraulic snubbers have a piston which is relatively unconstrained in motion at low displacement rates. At high displacement rates the piston “locks up”, that is, the force required to move the piston increases substantially, usually as a result of the closing of a valve.

Types & Sizes

Technical Information

Installation & Maintenance

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    General Dimensions & Specifications

    Download Anchor / Darling Catalog

    Hydraulic Snubbers Guide

    The style “AD” Hydraulic Shock Arrestor is a manifold design hydraulic component consisting of a high pressure main cylinder, a flow control section which contains dual stage velocity sensitive poppet valves, and a spring energize reservoir.

    Fig510ad 511ad snubber 2

    For use on piping systems or equipment when unrestrained thermal movement must be allowed, but which must be restrained during impulsive or cyclic disturbance. The unit is not effective against low amplitude, high frequency movement. The preferred usage with standard settings is to prevent destructive results due to earthquakes, flow transients, or wind load. Special settings are available to absorb the continuous thrust resulting from safety valve blow-off or pipe rupture.

    Size Range:
    PTP offers seven sizes with cylinder bores of 1 1/2 to 8 inches. These units have a normal load range of 3,000 lbs. to 130,000 lbs. All are made to include reservoirs in 6, 12, or 18 inch strokes, except the 1 1/2 inch size. The 1 1/2 inch size is offered only in 6 & 12 inch strokes only. Snubbers, as they are sometimes referred to, are available with remote reservoirs.

    Size Selection:
    The selection of size depends on the anticipated force and thermal movement of the protected piping or equipment. It is recommended that the selected cylinder stroke be a minimum of the anticipated thermal movement, plus 20%.

    Basic Operation:
    The piston rod is free to move in either direction with no restrictions to the fluid flow for all piston velocities up to the activation velocity. At activation velocity the poppet valve, internal to the snubber, closes. Closure of the poppet in either tension or compression greatly reduces the fluid flow through grooves in the poppet at rated design capacity of the unit is termed the “ bleed rate”. When the applied velocity of the unit becomes zero the poppet valve opens once again, allowing free piston movement.

    Standard Design Features:
    – Piping and/or equipment movement is controlled by tamperproof dual stage flow control poppets designed with self-cleaning orifices.
    – Furnished as a complete, compact and efficient unit, ready for immediate use.
    – Manifold configuration requiring no external piping.
    – Spherical, self-aligning ball bushings allow for ±5º of angular motion or misalignment.
    – Stable premium grade, antiwear hydraulic fluid.
    – Pressurized hydraulic reservoir allows mounting in any spatial orientation.
    – Virtually no resistance to normal thermal movements of the piping.
    – Large restraining forces compared to size.
    – Functions in restraining tension and compression loads.
    – Designed for continuous operation up to 200°F with brief transients to a maximum of 300°F.
    – Stroke position is measured from a machined groove located at the piston rod wrench flats.
    – Fluid Level in the unit, thereby eliminating estimate of reserve fluid level.

    Optional Design Features:
    – Remote Reservoir Mounting
    – The snubber’s pressurized reservoir can be remotely mounted for inaccessible locations.
    – Integral Relief Valve- A non-adjustable valve, which is factory preset at 133%, or 200% of rated load.
    – Protective Boot- Installed over piston rod for protection against corrosive or outdoor environments.
    – Rigid Stud Application- When no thermal growth is anticipated after lock-up, an optional poppet valve, without bleed, can be furnished. Must be ordered with optional integral relief valve.

    Hydraulic Snubber Equation

    Factory Pre-set:
    The units are shipped from the factory complete, tested, reservoir filled to capacity and piston rod preset to mate with pin to pin installation dimension. To determine factory pre-set dimension perform the following calculations.


    In addition to the mechanical equipment described in this brochure, Anchor/Darling Enterprises also offers a complete line of hydraulic snubbers.
    • hydrA/Damp — Our advanced design, corrosion resistant hydraulic snubber, for superior performance within many environments.
    • B-P Style — Our well-established (formerly Bergen-Paterson) manifold design hydraulic snubber, eliminates external tubing and its pressurized reservoir allows installation in any spatial orientation.
    • Non-Nuclear — Our commercial snubber design, for use within fossil/co-gen/petro-chernical plants that require proven performance at economical prices.
    For additional information on any of our hydraulic or mechanical snubbers, contact the regional office nearest you.


      Download Fig. 510AD and Fig. 511AD PDF

      Fig 510AD Short Strut & 511AD Adjustable Strut Hydraulic Snubbers

      Fig. 510AD Short Strut Hydraulic Snubber and Fig. 511AD Adjustable Strut Hydraulic Snubber510ad 3d511ad 3d  

      ORDERING: Specify figure number, description, cylinder size, stroke, load, thermal movement, overall length, and piston end option. If a pipe clamp is required, please specify nominal pipe size or special O.D., pipe temperature, and any additional option features (i.e. integral relief valve or remote reservoir mounting) or special settings required.


      CylinderApprox. Weight (1)H Min.
      P-P Min. (2)Load Rating (KIPS)ABDD1EGLMW1SBB
      1   1/26351621323/42   1/22   3/431   1/161   1/4523/40.656
      2   1/267016   1/223   1/4102   1/2133   1/23   3/41   1/21   3/46310.875
      128322   1/229   1/4
      189628   1/235   1/4
      3 1/4612517   3/827   1/82041   1/254   3/45   1/22 1/22   1/47   3/84   1/41   1/21.312
      1214523   3/833   1/8
      1816529   3/839   1/8
      4615528   1/228   1/23041   1/254   3/46   1/22   1/22   1/28   1/24   1/41   1/21.312
      1218034   1/234   1/2
      1820529   3/440   1/2
      5625518   1/431   3/4505   1/227683   1/23   1/410   1/45   1/21   7/81.75
      1229024   1/437   3/4
      1832530   1/443   3/4
      6641019   1/233   3/47062   1/476   1/28   1/243   3/411   7/85   3/42   1/41.968
      1246525   1/239   3/4
      1852031   1/245   3/4
      8680521   3/1641   7/161308   1/23101012   1/25   1/24   3/4167   3/42   7/82.625
      1289027   3/1647   7/16
      1897533   3/1653   7/16


      1   1/264032   3/41006   1/47   1/2
      124738   3/4100
      185444   3/4100
      2   1/267536   1/41207   1/48   3/4
      129042   1/4120
      1810548   1/4120
      3   1/4613041   5/81209   1/29   1/4
      1215047   5/8120
      1817053   5/8120
      4620044   1/812010   1/89   3/4
      1222550   1/8120
      1825056   1/8120
      5633049   1/212012   1/210   3/4
      1236555   1/2120
      1840061   1/2120
      6653053   3/812013   3/411   5/8
      1259059   3/8120
      1864565   3/8120
      86105062   11/1612016   1/413   3/8
      12114068   11/16120
      18122574   11/16120

      1Add cold piston setting for install length. These values reflect cylinders having 6" of stroke.
      2Load must not be applied utisde 10º included angle cone of action to the pipe clamp axis w/o special authorization.
      Fig. 510AD & 511AD: Dimensions
      CYLINDER SIZEAFig. 510AD P-P Retracted1Fig. 511AD P-P Retracted1MAX.RECOM. NORMAL LOAD2 (lb.)
      1 1/222132 3/43,000
      2 1/22 1/223 1/436 1/410,000
      3 1/4427 1/841 5/820,000
      4428 1/244 1/830,000
      55 1/231 3/449 1/250,000
      6633 3/453 3/870,000
      88 1/241 7/1662 11/16130,000

        Fig. 2100 is discontinued. Please refer to Fig. 510AD & Fig. 511AD.

        Fig510ad 511ad snubber 3

        510ad 3d

        511ad 3d
        ORDERING: Please specify figure no., cylinder size, stroke, load, cold and hot piston settings, and piston end option. If clamp is required, please specify nominal pipe size, or special O.D. and clamp material. Please specify or describe any additional optional features or special settings required

          • Please be as specific as possible using Fig. Number and/or Type. You may also upload files below.
          • If this is an urgent request please use our 24/7 Emergency Request Service!
          • Please attach a drawing, photo, document or other file(s) to help us generate your quote.
            Drop files here or