Plastic Insert

Plastic Insert

Tube insert is inserted into the end of a heat exchanger tube to provide protection to the tube mouth ends of a shell & tube type heat exchanger. The purpose of the tube insert is to either be sacrificial to the effects of inlet-end erosion, corrosion and impingement, or induce a fluid to fall on the ID of a tube in a falling film exchanger, or transfer extremely high heat past the tube sheet to the exchanger tubes.

The following problems take place in the shell & tube type heat exchangers

• Tube-end erosion/corrosion
• Stress corrosion cracking
• Crevice corrosion
• Localized pitting
• Ammonia grooving
• Improper tube expansion
• Weakened tube-to-tube sheet joints

For the above problems, VP Engineers (VP ENGINEERS) offers its most cost-effective tube repair, shield/seal, also known as a tube insert or ferrule. Although inserts are typically only 6" - 12" long, some applications have required shield lengths up to 14 feet! Unfortunately, some exchangers suffer from full-length problems. In this case, VP ENGINEERS full length tube liners can be a very attractive alternative to a partial or full re-tubing.

Material of Construction (MOC):

Plastics: Nylon (Polyamide), LDPE and PP

Plastic inserts comes with two types of head design

Bonnet

Bonnet head which is used when the tube slightly projects for about 3 to 5 mm outside the tube sheet. The bonnet head encapsulates the projection in such a way that the high velocity impingement does not affect the tube mouth end & thus ensures the longevity of tube mouth end & tube.

Flared Head

Flared head which is used when the tube does not project outside the tube sheet. Plastic inserts are generally preferred in surface condensers of a power Plant. Nylon tube inserts can be used for up to 150°C, for some special applications even PTFE tube inserts are used for temperatures up to 250°C. Plastic tube inserts are used in different types of heat exchangers of different duties for temperatures up to 800°C.