PNGRB Guidelines: 22 Root causes for threat to pipeline integrity

What is PNGRB?

PETROLEUM AND NATURAL GAS REGULATORY BOARD is a statutory body in India, constituted under the act of Parliament of India, namely Petroleum and Natural Gas Regulatory Board Act, 2006.

What is PNGRB’s objective

To regulate refining, transportation, distribution, storage, marketing, supply and sale of petroleum products and natural gas.To ensure uninterrupted supply of petroleum, petroleum products and Natural Gas


Why is PNGRB rules and regulations crucial?

To improve and protect personnel, property, public and environment from pipeline accidents.Pipeline accidents and it’s severity

Pipeline accidents and it’s severity

  • Gasoline ( Petrol) transporting pipeline exploded in the town of Tlahuelilpan, in the Mexican state of Hidalgo.
  • The blast killed at least 137 people.
  • A massive fire broke out, following a blast in Gas Authority of India Limited (GAIL) from 18″ size underground gas Pipeline at Nagaram, Andhra Pradesh, India.
  • The blast killed about 23 people

How to eliminate the pipeline accidents?

  • One of the key step to eliminate the pipeline accidents is to identify the root causes, which possess a threat of pipeline integrity.
  • According to PNGRB guidelines, there are 22  root causes can cause potential threat to pipeline integrity.
  • The 22 root causes for threat to pipeline integrity is classified by Pipeline Research Committee International (PRCI), hence this classification applies quite global and not restricted to Indian Guidelines.
  • These 22 root causes can be seen in ASME.B31.8S – Managing System Integrity of Gas pipelines.

Time Dependent Threats

  • External Corrosion (happens on the surface of the pipeline)
  • Internal Corrosion(    (happens inside the pipeline)
  • Stress Corrosion Cracking  (growth of crack formation in a corrosive environment)
External Corrosion

Stable Threats

  • Manufacturing related defects
    • Defective pipe seam
    • Defective pipe 
  • Welding / Fabrication related
    • Defective pipe girth weld (Girth weld – welding done on the circumference of pipeline to join two pipelines)
    • Defective fabrication weld ( Fabrication – welding,  cutting, bending and assembling of metal parts to form a specific shape)
    • Wrinkle bend or buckle ( buckling is deformation caused in the pipeline due to lateral tensile stress)
Stable threats

Time independent Threats

  • Third party /mechanical damage
    • Damage inflicted by first, second or third party (instantaneous /immediate failure)
    • Previously damaged pipe (delayed failure mode)
    • Vandalism ( deliberate destruction of public/private property)
    • Rat bites Electric Arching
  • Lightning
  • Weather related any damage
  • Heavy Rains or Floods
  • Earth Movements

Root causes for threat to pipeline integrity

  • Unknown” – one of the causes always reported by the operator, which is the 22nd root cause.
  • Miscellaneous:
    • Other threats may be applicable based upon the land pattern:
    • Creek Area effects
    • Muddy Land effects
    • River bed movements

These threats may lead to pipeline to scour, corrode, vibrate and get damaged.

Prevention and Mitigation actions

Pipeline failure threats could be prevented and mitigated through,

Mitigation through repair actions (For corroded area, loss of wall thickness, cracks, dents)

  • Mitigation through Preventive actions
    • Patrolling the pipelines and associated facilities
    • Maintenance and inspection of crossings
    • Proper pipeline cleaning/ pigging
    • Inspection of cathodic protection system
    • Coating survey