15 Piping Interview questions

Field Instrumentation
1

Piping-Design
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1. What are the main duties of the piping inspector?

  • Material receiving an inspection

  • Storage & preservation

  • Cutting,assembly & fit-up

  • Pre-welding inspection

  • Visual inspection of socket & threaded joints

  • Pneumatic test for reinforcing pad

  • Pickling & passivation

  • Database reporting

  • Visual inspection of completed spools

  • Piping pre-inspection & spool erection

  • orifice flange inspection

  • Pipe support inspection

  • Verification of slope

  • Internal cleanliness

  • Valve installation

  • Piping flange joint inspection

  • Pre-test punch listing

  • Hydro testing

  • Precommissioning

2. What is the ASME code followed for design of piping systems in Process piping?

(i) B 31.1 (ii) B 31.3 (iii) B 31.5 (iv) B 31.9

3. How can flanges be classified based on facing?

  • Flat face. (FF)

  • Raised face. (R/F)

  • Tongue and groove. (T/G)

  • Male and female. (M/F)

  • Ring type joint. (RTJ)

4. How can flanges be classified based on Pipe Attachment?

  • Slip-on - The Slip-on type flanges are attached by welding inside as well as outside. These flanges are of forged construction

  • Socket Weld : - The Socket Weld flanges are welded on one side only. These are used for small bore lines only.

  • Screwed: - The Screwed-on flanges are used on pipe lines where welding cannot be carried out.

  • Lap Joint : - The Lap Joint flanges are used with stub ends. The stub ends are welded with pipes & flanges are kept loose over the same.

  • Welding Neck : - The Welding neck flanges are attached by butt welding to the pipe. These are used mainly for critical services where the weld joints need radiographic inspection.

  • Blind : - The Blind flanges are used to close the ends which need to be reopened.

  • Reducing : - The reducing flanges are used to connect between larger and smaller sizes without using a reducer. In case of reducing flanges, the thickness of flange should be that of the higher diameter.

  • Integral : - Integral flanges are those, which are cast along with the piping component or equipment.

5. Define Hydrostatic test, Pneumatic test, Pressure test, Service test:

Hydrostatic Test: A pressure test carried out using water or other liquid authorized as the test medium.

Pressure Test: A pressure test carried out using water or other liquid authorized as the test medium

Service Test: A leak test conducted at operating pressure using the service fluid.

6. Where do we attain test pressure and why?

We achieve test pressure at the highest pressure gage because the impact is reduced by 1 bar pressure every 10 m height due to gravity.

7. How do you verify (name several items to check) that the correct piping material is used?

Material specification, Pipe size, schedule, length, flange face rating, olet size rating, threaded/socket weld type, MTC, PMI report.

8. How do you check piping for the correct schedule?

Verify pipe material thickness by Vernier at end or stenciling by the manufacturer (visual) or heat number, MTC’s product traceability

9.What is the difference between torqueing CS and SS bolting?

CS:- Yield strength High; Torque value High

SS:- Yield strength low; Torque value low

10. What are the types of gaskets?

Based on the type of construction, gaskets are classified as: -

A. Full face. B. Spiral wound metallic. C. Ring type. D. Metal jacketed. E. Inside bolt circle

11. What do you mean by jacketed piping?

Piping which is recognised as providing the most uniform application of heat to the process, as well as maintaining the most uniform processing temperature where steam tracing is not capable of maintaining the temperature of the fluid constant.

12. Why do we provide Drip leg in steam line?

To remove the condensate when there is a rise in condensate in the pipe along the flow direction. If drip leg is not provided, the condensate which form inside the pipe which results in Hammer effect.

13. What is the main use of ASTM A53 & A106 Gr.B pipes?

ASTM A53 pipes are mainly used for utility services whereas A106 Gr. B pipes are used for high Pressure & high temperature services.

14. What is the maximum diameter piping allowed in hazardous service?

Socket welding:- 2 “for maintenance & minor alteration & 1-1⁄2” for new construction.

Threaded:- 1-1⁄2 “for normal fitting & valve and a maximum of 2” for maintenance purposes, minor field modification of the current piping scheme.

15. Difference between carbon steel and stainless steel?

CS:- Low cost, no chromium content, appropriate up to 350 degrees C for non-corrosive service, max carbon 0.3%.

SS:- Contains more than 12% Cr, 0.08% C, suitable for corrosive, cryogenic, high-temperature services, expensive.