How to handle failure of PTFE lined pipes and fittings

  • Billions of dollar Loss of pharma and chemical plant due to failure of equipment
  • Effect of failure, production loss, accidents, fire and environmental damage
  • Piping Failure can be – internal leakage, external leakage, failed lining or failed metal piping itself.

Reason of failure – defective pump, reactor, process malfunction, chemical reaction, sudden rise of temperature or pressure. Human error, valve failure, sensor defect or maintenance error.

How to handle failure of PTFE lined pipes and fittings

Lined piping failure detection, early detection of lining failure can be seen on vent hole given on pipes and fittings. In case of early detection there are chances that batch or material under process can be saved from mixing of corrosion with process fluid or spillage of material on floor.

During the inspection, first step is to stop process or plant so failed lined pipe or fittings can be replaced. It is also recommended for inspection of all the nearby connected lined pipes and fittings since there are chances that if failure was due to pump or any external reasons then there are chances that other piping would also be damaged and need to be replaced.

Once lined product uninstalled, it is mandatory to check first what process its used and how hazardous that chemical for human contact or it may have material which creates gas and that’s harmful. After checking if its safe to check and if possible better to clean it for surface inspection.

In some cases of failure where due to high pressure or high vaccum lining damaged, we see change of shape of lining so during cleaning or inspection, it would be better not to change for further evaluation in case required because maintaining same condition will be helpful to understand engineer reason of failure.

While doing inspection, its better to note operating parameters exactly and also process fluid and properties of material. In case of failure of welding or metal portion, there are chances that quality of welding was poor or due to highly corrosive nature of fluid after lining failure weld joint got weaker and metal part damaged.

Depending on the situation, its better to take pictures of failure even before uninstalling and after removal from the piping.

Common type of lined pipe and fittings failure

  • Cracked flaring of PTFE tube on flange area
  • Bulging of PTFE tube due to vacuum
  • Pin hole in lining
  • Cracked tube of lined pipes
  • Cracked lined surface of PFA/FEP lining
  • Metal joint cracked from welding
  • Cast part failure in lined tee or lined cross or lined reducer
  • Gasket failure in joint
  • Shrink lining inside metal
  • Lining lifted from metal surface
  • Pieces of PTFE fibers inside pipe
  • Pieces of lined material inside process
  • Burned material of lining
  • Shrinkage of lining
  • Cracked from drilling area of flange
  • Lined valve failure
  • Leakage due to loose bolting
  • Leakage due to failure of PTFE bellow
  • Spillage due to cracked lined bend