Constant Spring Hangers

Constant Spring Hangers are a reliable counter-balance with the counterbalance force imposed by a spring coil

Where to Buy Constant Spring Hangers

SEARCH

What Are Constant Spring Hangers?

A Constant Spring Hanger – also known as a Constant Effort Hanger or Constant Effort Support – is a reliable counter-balance with the counterbalance force imposed by a spring coil. By using varying lever arms and spring coil load variation, an accurate constant supporting force is obtained. Constant Spring Hangers provide constant support forces for piping systems which move vertically due to thermal expansion or contraction and where the transfer of support load to adjacent hangers and/or equipment is not acceptable.

These hangers have been thoroughly time-tested as evidenced by years of successful operation in a large number of steam gen- erating stations, oil refineries and chemical plants throughout the world.

Constant spring hangers are available in seven different types and a broad variety of sizes to accommodate a wide range of loads, movements and hanger arrangements.

B-Type Constant Spring Hanger

B-Type Constant Spring Hanger

D-Type Constant Spring Hanger

D-Type Constant Spring Hanger

F-Type Constant Spring Hanger

F-Type Constant Spring Hanger

S-Type Constant Spring Hanger

S-Type Constant Spring Hanger

U-Type Constant Spring Hanger

U-Type Constant Spring Hanger

V-Type Constant Spring Hanger

U-Type Constant Spring Hanger

VB-Type Constant Spring Hanger

VB-Type Constant Spring Hanger

VBS-Type Constant Spring Hanger

VBS-Type Constant Spring Hanger

How to Fabricate a Constant Spring Hanger

As is is with the variable spring hangers, the constant’s casings are also cut from standard steel pipe, and other parts are cut from steel plate. The constant spring hangers employ a pivot arm that has low friction bearings. A helical coil is also used.

All Constant Hangers are manufactured in conformance with government regulations and industry codes where applicable. Among these are the American Society of Mechanical Engineers’ – Codes for Pressure Piping (ASME B31.1 Code for Power Piping and ASME B31.3 Code for Chemical Plant and Petroleum Refinery Piping), the Manufacturers Standardization Society Standards SP-58 and SP-69 and the U.S. Government Federal Specification WW-H-171 for pipe hangers and supports.

Constant Spring Hanger Components

Constant Spring Hanger Components

How to Install and Set a Constant Spring Hanger

Constant spring hangers are designed so that they can be installed by an average field worker with little to no difficulty. Placing the hangers in position and adjusting them to carry the desired load at the desired position is easily accomplished. All suspension style constant hangers are designed so that the top connection can be removed in the field and can be bolted or welded separately to the supporting structure or suspended from rods. The hanger frame and casing can then be easily attached by reinserting the removable pin or pins.

All constant effort hangers have upper and lower stops to limit travel. Hangers with downward travel (pipe moves downward from installed to operating) will be locked (pinned) in the installed position in order to handle the hydrostatic test loading. Hangers with upward travel (pipe moves upward from installed to operating) will be locked (pinned) in the installed position which eliminates the necessity of pulling the hanger to the bottom of the travel when connecting the load rod in the field. All hydrostatic tests should be performed with the constant locked in the installed position. If desired, constant spring hangers can be supplied locked at any desired point in the total travel range. In all cases, the lock pin can easily be removed by hand by adjusting the turnbuckle on the load carrying rod until the pin is loose. This lock must be removed at the final adjustment or the hanger will not function.

After the hydrostatic test is performed, the final adjustment should consist of turning the turnbuckle so that the hanger is not resting on the travel stop in the installed position. An inspection should be made after the system is in service to insure that the travel indicator is located at the operating position on the travel scale.

When the supported piping system is required to be re-hydro tested after start-up, all constant effort hangers should be re-pinned in the installed position. All hangers should be adjusted, by the turnbuckle, until the pin holes are aligned and the pin can be re-inserted. In a piping system where “cold spring” must be utilized to align a piping system or to pre-stress it, planning ahead is encouraged so that the line can be supported before, during and after the cold spring exercise by adjusting the turnbuckle within its limits.

Travel Indication

The indicator arrow (mounted on the pivot arm) and travel indicator plate (shown here) mounted on the hanger frame indicate the position of travel. The arrow should point to a point on the travel indicator plate under all operating conditions.

For hangers with downward travel as the pipe moves from installed to operating, the indicator arrow must be near the top of the range when the load rod is properly adjusted for the installed position. For hangers with upward travel as the pipe moves from installed to operating, the indicator arrow must be near the bottom of the range when the load rod is properly adjusted for the installed position.

Travel Indicator Plate

Travel Indicator Plate

Travel Indication 1
Travel Indication 2

Field Load Adjustment

The support load on each constant spring hanger is set on a hydraulic press and calibrated with a load cell before shipment. Adjustment of the hanger load will modify the load supported by the hanger and may invalidate the design engineer’s stress calculations.

However, in order to provide for cases where the load to be supported is different from the specified load or where a change in hanger location becomes necessary, the hanger is provided with a load adjustment mechanism on the tail of the spring rod. Field adjustment can increase or decrease the specified load by as much as 10%. As a result, a hanger carrying 2,000 lbs. can be field adjusted to carry loads from 1,800 to 2,200 lbs.

To adjust the load, loosen the jam nut to which the load sleeve is attached. Turn the main spring rod nut clockwise to increase the load and counter clockwise to decrease the load. When the jam nut is returned to its original position against the main nut, the amount of load adjustment can be read from the position of the indicator on the load scale. When adjustment is completed the jam nut must again be tightened snuggly.

The extreme end of the spring rod is equipped with a permanent stop to pre- vent the complete removal of both the jam nut and sleeve, and the main spring rod nut. Under no circumstances should an attempt be made to re- move these nuts from the end of the spring rod.

Travel Indicator Plate
Field Load Adjustment

ASME Specification

B31.1

American Society of Mechanical Engineers’ – Codes for Pressure Piping (ASME B31.1)

Standard Constant Spring Hangers

Type B – Horizontal Base

The horizontal base Type B constant spring hanger is designed for use in limited headroom applications where available structural support members are above and close to the pipe. The B-type may be mounted on top of the supporting steel or inverted beneath the support steel in a trapeze arrangement. The load rod connection is a bushing or a spherical bearing if desired to permitthe support rod to swing in both directions.

B-Type Constant Spring Hanger 2

B-Type Constant Spring Hanger

B-Type Constant Spring Hanger in the Field 2

B-Type Constant Spring Hanger in the Field

These twin B-Types are supporting the pipe via a trapeze.

B-Type Constant Spring Hanger in the Field 1

B-Type Constant Spring Hanger in the Field

This B-Type is supporting the pipe using a steel clevis and welding lug

Type D – Double Suspension

The Type D double suspension point constant spring hanger is designed to be able to support the heaviest support loads and the longest actual travels. This D-type is furnished with two lugs welded on the top of the frame plate. The lugs can be oriented either along the axis of the hanger casing or perpendicular to the axis of the hanger casing. Mating attachments can be provided with rods and clevises and beam brackets.

D-Type Constant Spring Hanger 2

D-Type Constant Spring Hanger

D-Type Constant Spring Hangers

Twin D-Type Constant Spring Hangers

D-Type Constant Spring Hanger in the Field

D-Type Constant Spring Hanger in the Field

This D-Type is supporting the pipe using a steel clevis and welding lug and is suspended by welding lugs

Type S – Single Suspension

The Type S single suspension point constant spring hanger is designed for use with a single rod or welding lug top connection. When the S- type hanger is suspended by a single rod, the entire hanger can be rotated 360º to avoid interference. When headroom is limited, an alternate top connection, a lug, can be furnished which attaches directly to the building structure.

S-Type Constant Spring Hanger 2

S-Type Constant Spring Hanger

S-Type Constant Spring Hanger in the Field 1

S-Type Constant Spring Hangers in the Field

These twin S-Type hangers are suspended from the structural steel with a welding lug and are attached to the pipe via a riser clamp

S-Type Constant Spring Hanger in the Field 2

S-Type Constant Spring Hanger in the Field

This D-Type is supporting the pipe using a 3-Bolt pipe clamp and is suspended by a welding lug

Type U – Upthrust

The upthrust support is designed for use when the pipe must be supported from below and when there is room to extend the casing horizontally. The Type U constant spring hanger upthrust support may be attached to the supporting structure or foundation, by either bolting or welding. Generally, a low friction slide bearing is supplied on the top of the load table so that the member being supported by the upthrust support can move laterally with minimal resistance. Vertical alignment of the load table is maintained by PTFE slide bearings during support movement.

U-Type Constant Spring Hanger

U-Type Constant Spring Hanger

Type V – Vertical

The Type V single suspension point constant spring hanger is designed for use with a single rod or welding lug top connection and can be used when space limitations restrict the use of a model with a horizontal spring casing. When the V-type hanger is suspended by a single rod, the entire hanger can be rotated 360º to avoid interference. When headroom is limited, an alternate top connection, a lug, can be furnished which attaches directly to the building structure.

V-Type Constant Spring Hanger

V-Type Constant Spring Hanger

Twin V-Type Constant Hangers

Twin V-Type Constant Hangers in the Field

These twin V-Type hangers are suspended from the structural steel and are supporting the pipe via a trapeze

Type VB – Vertical Base

The vertical VB-type vertical base constant spring hanger is designed for use when dimensional limitations restrict the use of a horizontal type hanger. The VB-type hanger may be mounted on top of the supporting steel or two units may be inverted and used in a trapeze configuration, as shown on the applications page. Attachment to the structure may be made by either bolting or welding.

VB-Type Constant Spring Hanger

VB-Type Constant Spring Hanger

VB-Type Constant Spring Hanger in the Field

VB-Type Constant Spring Hanger in the Field

This VB-Type hanger is supported by two channel pieces and is connected to the pipe via a welding lug

VB-Type Constant Spring Hanger in the Field 2

VB-Type Constant Spring Hanger in the Field

These twing VB-Type hangers are suspended from structural steel and are supporting a cryogenic shell with a trapeze

Type VBS – Vertical Base Stanchion

The Type VBS vertical base stanchion constant spring hanger is designed for use when the footprint of the hanger must be small and the pipe must be supported from below with a strut or from above the supporting structure. The Type VBS support may be attached to the supporting structure, either by bolting or welding.

VBS-Type Constant Spring Hanger

VBS-Type Constant Spring Hanger

VBS-Type Constant Spring Hanger in the Field

VBS-Type Constant Spring Hanger in the Field

This VBS-Type hanger is attached to the floor and supports the pipe from underneath

Where to Buy Constant Spring Hangers

SEARCH