The following data is required to be specified while inquiring/ordering for a constant spring,
i. The exact Hot or Operating load required to be ii. supported during the working condition.
iii. Hydrostatic test load.
iv. The total travel and its erection.
v. The direction of travel, either upwards or downwards from the erected position.
vi. The set pin locking position (Top, Middle, Bottom or as required).
vii. The basic model.
viii. Requirement of bottom accessory components such as rods, clamps etc.
• Any hazardous environmental conditions.
• any special finish on the body such as galvanizing etc.
5.2.1 How to select the series?
5.2.2 How to determine the type? 5.2.3 How to determine size?
5.2.2 How to determine the type
The type of variable spring hanger to be used depends upon the physical characteristics required by the suspension problem I.e. available head room, pipe to be supported above the
spring or below the spring etc. The type should be selected from the seven standard types available. (See sketch for types A through G)
5.2.1 How to select the series
The selection of the hanger series shall be done to limit the supporting force within the allowable range. In choosing between the series VS1, VS2 and VS3 it must be ensured that the calculated movement will fall within the working load range. The series VS1 has the maximum variation in supporting force and hence is not a competitive selection but an invention of necessity where head room is not sufficient to use VS2.
Good engineering sense combined with available space and reasonable economic considerations should ultimately determine which series of variable spring hangers should be used.
5.2.3 How to determine size
For determining the size of the hanger the load deflection table shall be referred. In order to choose the proper hanger size the data required is the actual load or the working load (also called the hot load) and the amount and direction of the pipe line movement from cold to hot .
Locate the hot load in the table. To determine the cold load, read the spring scale up or down for the amount of expected movement. The chart must be read opposite from the direction of pipe movement. The load arrived is cold load.
If the cold load falls outside the working load range of hanger selected, relocate the hot load to the adjacent
column and find the cold load. When both the hot and cold loads are within the working range of a hanger, the size of the hanger is the number found at the top of the column.
Should it be impossible to select a hanger in any series such that both loads fall within the working range, consideration should be given for a constant spring hanger. Once selected, the percentage load variation shall be checked as follows:
Travel x Spring Rate x 100 Load Variation Percentage =
Hot load
SPECIFICATION FOR ORDER
The following data is required to be specified while inquiring/ordering for a variable spring:
I.
II. The exact hot or operating load required to be supported during the working condition.
III. Hydrostatic test load.
IV. The calculated vertical movement and
V. The direction of travel, either upwards or downwards from the erected position.
VI. The hanger series, type and size.
VII. The allowable percentage variation of load from cold to hot. VIII. Requirement of accessory components such as rods, clamps
etc.
IX. Any hazardous environmental conditions.
X. Any special finish on the body such as galvanizing etc. XI. Tag or Identification number.
COMMISSIONING OF SPRING SUPPORTS
2.5.1 Securely attach the spring to the building structure by identifying and locating at each support point in
accordance with hanger installation drawing. The location should be such that the hanger should be perpendicular in the hot or operating position/the
load should act vertical.
2.5.2 Make sure the moving parts are unobstructed. 2.5.3 The locking should not be disturbed till complete
erection is over. The lock that makes the support work as a rigid support during erection, hydrostatic
testing or chemical clearing etc.
2.5.4 The locking pins must be removed after the hanger is fully loaded to put the piping systems into
removed by the hand after adjusting the distance between the hangers and pipe by rotating the turn buckle.In case of foot mounted supports the load flange is rotated till it touches equipment/pipe being supported. Then the threaded bush with hexagonal sides is rotated so that it moves up and the load is gradually transferred on to the support. The preset pin becomes loose when the pipe load becomes the preset or factory
calibrated load. The support is then ready for use.
2.5.5 Once the preset pin is removed the support allows movement up or down by the specified amount of travel in accordance with the expected pipe
movement.
2.5.6 When the line is in operation, carefully check the support for its free movement. Generally no further