The basic parameters considered during the selection of supports are mentioned below:
1) Process design conditions
2) Pipe material of construction
3) Piping Loads including Piping weight, fluid,weight, Valves,inline instruments etc.
4) Insulation material,thickness,density & specification.
5) Piping General Arrangement drawing
6) Thermal forces,moments & displacement of Piping
7) Occasional loads: Hydrotest loads, Sesimic loads, wind loads etc.
As per clause 321.1.1 of code ASME B31.1, the objective of support design is as below:
The layout and the design of the piping and its supporting elements shall be directed towards preventing the following
1. Piping stresses in excess of those permitted in the code.
2. Leakage at joints.
3. Excessive thrust and moments on connected equipment (such as pumps and turbine).
4. Excessive stresses in the supporting (or restraining) elements.
5. Resonance with impose fluid induced vibrations.
6. Excessive interference with thermal expansion and contraction in a piping system, which is otherwise adequately flexible.
7. Unintentional disengagement of piping from its supports.
8. Excessive piping sag in systems requiring drainage slope.
9. Excessive distortion or rag of piping (e.g. thermo plastics) subject to creep under conditions of repeated thermal cycling.
10. Excessive heat flow, exposing supporting elements to temperature extremes outside their design limits.
Considering the above criteria, piping supports shall be selected and designed.
The basic type of supports used in refinery are:
Anchors: It restricts all six degree of freedom (i.e,Rotational, Logitudinal & Axial).
Guides: It restricts the longitudinal movements but free to move in rotational and axial.
Line Stops: It restricts the axial movements but free to move in rotational and longitudinal.
Rests: It takes the vertical loads generated due to pipe weight, fluid weight,thermal loads and occasional loads.