Acrefine Engineering
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Seismic Snubbers

Restraints that stand beside open springs and rubber mounts and stay out of contact in normal running. In an earthquake or high wind they catch the equipment within 6 mm (1/4″), on rubber-lined faces that take the edge off the shock load.

See the range
Air handling unit on rubber pads along its galvanised base rail, held by black AS-Z snubbers bolted to the plinth, at the Abdi İbrahim pharmaceutical plant in Istanbul

The range

Chosen by direction, then by load

A snubber is selected for the directions it has to hold, then sized to the force. We supply snubbers directly, selected and placed with the seismic calculation for the equipment.

  • AS-A all-directional snubber: two interlocking black steel parts with slotted fixing holes and rubber-lined contact faces
    AS-A

    All-Directional Snubber

    Two interlocking parts, one fixed to the structure and one to the equipment, rubber-lined on every contact face.

    All directions · in pairs on opposite sides · up to 10,000 kgf as standard

    Ask us for a selection
  • AS-Z snubber: compact black body with a thick ribbed rubber cushion and a bolt-down flange
    AS-Z

    Uplift & Lateral Snubber

    Holds lateral movement and uplift; placed on all four sides of the equipment to assure all-directional restraint.

    All directions · 3.5 mm rubber cushion · up to 2,500 kgf as standard

    Ask us for a selection
  • AS-C lateral snubber: black steel angle with a ribbed rubber face on the upstand
    AS-C

    Lateral Snubber (Bumper)

    Holds horizontal movement only, for equipment with no risk of overturning or uplift.

    Lateral only · at least four, facing in from every side · up to 6,000 kgf as standard

    Ask us for a selection
Large hot-dip galvanised all-directional snubber with a heavy gusseted body and a rubber-lined stop
Made to order

Tailor-Made Snubbers

Loads above the standard range, a hot-dip galvanised finish, or a snubber shaped to the equipment itself, such as a chiller delivered on flat steel legs. We design it to the equipment and the seismic demand.

Above 10,000 kgf · galvanised on request · shaped to the equipment base

Ask us for a selection

Datasheets, installation guides and certificates Downloads

Selection

Which way does it need holding?

Tall or narrow equipment can overturn and lift off its isolators; low, wide equipment mostly slides. The answer decides the snubber, and the calculation decides how many and where.

AS-AAS-ZAS-C
HoldsLateral movement and upliftLateral movement and upliftLateral movement only
PlacementIn pairs, on at least two opposite sidesOn all four sidesAt least four, facing in from every side
Use whenHeavy equipment that can overturn: chillers, generator sets, large pumps on inertia basesAir handling units, packaged units and fans on springs or rubber padsLow, wide equipment with no risk of overturning: tanks, skids and inertia bases on a level floor
Rubber cushion7 mm ribbed pad (API-S)3.5 mm7 mm ribbed pad (API-S)
Standard capacityUp to 10,000 kgfUp to 2,500 kgfUp to 6,000 kgf

Above the standard range, or equipment with an unusual base? We design tailor-made snubbers for the project.

Illustration: a large tunnel ventilation fan on a steel frame, carried on blue spring isolators and held by hot-dip galvanised AS-AR snubbers on concrete plinths

Featured solution

Marmaray, Istanbul

The rail tunnel beneath the Bosphorus, one of the largest infrastructure projects in Türkiye’s history. Before construction began, we carried out the complete seismic design of the tunnel’s electromechanical systems for Taisei Corporation.

We then supplied the products to the MEP contractor, Anel, and stayed with them on site for shop drawings and supervision: tens of thousands of seismic cable restraints, nearly every product in our range, and tailor-made AS-AR snubbers rated to 10,000 kgf under ventilation fans up to 2.8 m in diameter. The largest project in our history.

Learn more

Seismic restraint

Isolator and restraint, side by side

Equipment on open springs or rubber pads is free to move; that is how it isolates. A snubber stands beside the isolator, clear of the equipment in normal running, and closes on it only when the building shakes: the equipment stays resiliently mounted yet seismically restrained, with the gap held within 6 mm (1/4″).

A snubber holds in the directions it faces. All-directional restraint comes from placement: AS-A in pairs on opposite sides, AS-Z on all four. Uplift is held by the snubber’s own geometry and its fixing to the structure, not by a washer under a nut on the equipment bracket.

Every contact face is lined with rubber, so the first contact is cushioned rather than steel on steel. We size the snubbers and the isolators together, so the spring deflection and the snubber gap work as one system.

Related products

Open Spring Isolators Free-standing springs for vibration isolation, restrained by snubbers beside them.Rubber Mounts & Pads Rubber isolation under equipment, paired with snubbers in seismic zones.Seismic Isolators Isolation and restraint in one mount, where no separate snubber is wanted.

Related engineering services

Seismic Calculations for Equipment Anchorage and restraint calculations for floor-mounted equipment, to the code the project has to meet.Noise and Vibration Control Isolation design for equipment and mechanical rooms, sized to the criterion the project has to meet.

Describe the equipment and what it stands on.

We will select the snubbers, place them and size them to the seismic demand.

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