FREQUENTLY ASKED QUESTIONS

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Pipe is identified by NB and thickness is defined by schedule whereas tube is identified by OD.
SMAW: shielded metal arc welding
TIG: tungsten inert gas
  • Eccentric reducer: pump suction to avoid cavitations, to maintain elevation (BOP) in rack.
  • Concentric reducer: pump discharge, vertical pipeline etc.
No. Air pocket may form if concentric reducer is used at pump suction, which results in cavitations, and cause damage to pump. To, avoid this problem; eccentric reducer with flat side up is used in pump suction.
A pump is designed to handle liquid not vapour. Vapour forms if the pressure in the pump falls below the liquid’s vapour pressure. The vapour pressure occurs at the right of the impeller where a sharp pressure drop occurs. The impeller rapidly builds up the pressure which collapses vapour bubbles causing cavitations and damage. This is avoided by maintaining sufficient NPSH.
NPSH: Net positive suction head. NPSH is the pressure available at the pump suction after vapour pressure subtracted.
It is calculated as: static head +surface pressure head-the vapour pressure of your product-the friction loss in the piping, fittings and valves.
  • CS pipe= A106Gr.B
  • CS fitting =A234 GR.WPB
  • CS flanges=A105
  • AS pipe=A335Gr P1/P11
  • Cast CS valves= A216 Gr. WCB
Current (Amp) = [Diameter of welding rod (mm) x 40] +/- 20
Arithmetic average roughness height.
When fluid is gas, air or steam and cryogenic service-Topside
When fluid is liquid- Bottom side.
To remove condensate when there is a rise in the pipe along the follow direction. If we do not provide the drip leg in steam line, the condensate which forms inside the pipe will result in water hammer effect causing damage to piping system.
HPV –For removing air during hydro test
LPD - For draining water after conducting hydro test.
IBR- Indian boiler regulation act. Steam lines with conditions listed bellow comes under IBR purview Steam lines with design pressure is 3.5 kg/cm2 and above. Line size above 10’’ having design pressure 1 Kg /cm2 and above.
Destructive test: Bend test, tensile test, Impact test
Non Destructive test: DPT, MPT, Radiography and ultrasonic test.
  • Ans. Load of bare pipe+ insulation
  • Load of bare pipe + water fill
  • Load of valves and online equipment and instrument.
  • Thermal loads during operation.
  • Steam out condition, if applicable.
  • Wind loads for piping at higher elevation, If required.
  • Forced vibration due to pulsating now.
Expansion bellows are used absorb axial compression or extension, lateral shear and angular torsion developed in the pipes.