FULTON VMP Series - Fitting New Gaskets to Boiler Inspection Holes; Important Information

VMP-IOMM-2018-2
Fulton Ltd
Page 51
MAINTENANCE - 5
5.7 FITTING NEW GASKETS TO BOILER INSPECTION HOLES
5.7.1 IMPORTANT INFORMATION
TheVMPboilersarettedwithTOPOG-Egasketsinalltheinspectionholesoftheboiler.These
gaskets work very well and millions have been safely used over the last 30 years, however, it is
absolutely essential to observe a few simple rules in order to get the best performance from your
installation.
Elastomeric Vulcanizates, which form the basis of TOPOG-E gaskets, undergo degradation
from many sources including heat, oxygen, stress, and overdosing from certain types of water
treatment. This takes the form of material oxidation, hardening/embrittlement and cracking which
may result in gasket failure. Steps must be taken to minimise the effects of such attacks.
Water treatment and oxygen attack can be minimised by ensuring that the gasket is aligned
correctly so that only the extreme edges of the gasket are exposed. If a new gasket leaks after
ttingthisisalmostcertainlyduetoincorrectseatingoralignment.Assuchgasketsarevery
exibleitispossibletocuretheleakbyexcessivetightening,butsuchanactionwillseriously
reduce the life of the gasket and cause problems later.
Unduestresscanbeavoidedbytighteningjustsufcientlytostopanyleakagewhenttingcold
andbeforeringtheboiler.Starttheboilerandgraduallybringituptoworkingtemperature,
allowing the increasing steam pressure to take over and complete the seal. This will allow the
gasket material to contract naturally and follow the topography of the mating surfaces. The
securing nut can then be tightened gently by approximately a quarter of a turn, to ensure a ‘snug’
tandpreventthesealfrombeingbrokenwhentheboileriscoldandundernegativepressure.
Gentlewarmingoftheboileroninitialringaftermaintenancewillalsohelptoensurethatthe
rubber ‘cures to shape’. If the rubber post-cures, the elastic memory will be destroyed and any
initial over tightening will cause the gasket to become hardened and embrittled, leading to cracks
and eventual failure.
CAUTION

It is important that the instructions given in this section are adhered to.
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