The Problem With Rubber Expandable Tube Plugs VS. Silicone Expandable Tube Plugs

Recently, there has been some bad press with regards to the use of expandable tube plugs in the Power Plant Industry.  So bad actually that Plants are opting to pay out 10 times as much, for a tube plug that is perfect for  high pressure applications but OVERKILL for low pressure, low temperature heat exchangers and condensers.

Most of the bad press is due to failures seen with the black neoprene rubber type expandable plugs.  These are plugs made with the black rubber seals along with inexpensive spacers.  For some jobs, these plugs may work just fine, especially short term because the cost is low.

The cost is on par with the price of the pound in/”driven” plugs, either the two pin or a single tapered brass pin.  These types of plugs, while they will do the job, have two disadvantages over their expandable counter parts.
One is the fact that as soon as you pound in any plug into a tube, you have already created a scenario where; the tube has now expanded from it’s original shape, has potentially created cracks in the tube sheet and if the tube was taken out of service for flow reasons or scheduled to be tested at a later date, will need to be drilled out of the tube.  That will cost the Plant downtime and money and still you are left with tubes that have been permanently damaged.

The plug market is a niche market and one that often gets ignored until there is a significant problem with the Plants condensers/heat exchangers.  Best to be armed with the FACTS.

Here are the FACTS:

  • There are only a few types of plugs; Pound in/”Driven” pins, Expandables, and Mechanical/Explosives.
  • Pound in/Driven and mechanical/explosive plugs cause damage to tubes/tube sheets and if need to be removed will cost money and downtime.
  • Black rubber seal expandable plugs will crack, break down and lose their seal due to heat and cycling overtime.


  • Silicone expandable plugs will never break down, will last indefinitely, will NOT cause damage to tubes/tubesheet and will NOT have to be drilled out to be removed.


While the silicone expandable tube plugs cost a bit more in the short term due to preferable materials, such as non-water soluble washers and collars in conjunction with high temp silicone. You get what you pay for with our Hepco tube plugs. Our expandable plugs will not only LAST in the long term but COST less in the long term as they won’t cause any damage to your condensers and will seal indefinitely.

So the bottom line is this; when you have condensers and heat exchangers that don’t need a high pressure/high temp application, the BEST solution for plugging these tubes is HEPCO expandable silicone tube plugs. 


c/o Director of R&D for Hepco