Boiler Gaskets

Boilers are pressure equipment at risk of overheating in the sense of the pressure equipment guideline 97/23/EG and may only be sold if the manufacturer has provided proof that the necessary safety requirements of this guideline were adhered to by means of a conformity assessment procedure. The manufac- turer applies the CE-label and issues an EU-conformity declaration.

Harmonised product standards for boilers are:

• DIN EN 12952-1 up to 17: Water tube boiler
• DIN EN 12953-1 up to 14: Shell boilers
• DIN EN 14222: Stainless steel shell boilers

Different norms and regulations may also be applied. However, the manufacturer has to prove that he has fulfilled the necessary safety requirements of the pressure equipment guideline. Boilers or boiler plants have great risk potential due to the high stored energy and the high inner pressure. They are therefore plants which require monitoring as per the operational safety directive. Based on these regulations:

• boilers have to be checked by an approved inspection authority prior to commissioning
• approval for operation has to be obtained from the relevant authorities
• in certain intervals checks have to be repeated [inner and exterior checks, strength tests, functional test of the safety devices] by an approved inspection authority

In order to prevent possible risk when using non-metallic gaskets for sealing cover systems in boilers, the requirements for the relevant gasket system has been specified in the VdTÜV-infor- mation leaflet "Gaskets 100" [previously TRD 401, Technical Rules for Boiler]. The requirements in the clamping system and gasket, the test conditions and the marking of the gaskets are specified there.

The tests are carried out by VdTÜV. If the test results are posi- tive, then the component approval mark is awarded which has to be applied to the tested gasket. VdTÜV information leaflets are important with regards to the adherence to the pressure equipment guideline and the fulfilment of the AD 2000-policy. Boilers are fitted with access openings which are used to access the interior for revision work. The selection of the design is done in consideration of the condition of the clamping system. Boilers are equipped with oval sealing covers and interior lid. The lid is clamped using nuts and brackets and has a self-sealing effect in the event of overpressure.

The following IDT-boiler gaskets were specifically developed for use in oval sealing covers and meet all test requirements of the VdTÜV.

Gasket	Profile
FD01: WS 3860
FD01: WS 3885
FD20: WS 3885 outer eyelet 1.4571, 0,15 mm
FD30: WS 3885 inner- and outer eyelet 1.4571, 0,15 mm
WD10: WS 3860 corrugated ring 1.4751, 2 × 2 mm
WD30: WS 3860 corrugated ring 1.4751, 2 × 2 mm outer eyelet 1.4571, 0,15 mm
WD40: WS 3860 corrugated ring 1.4751, 2 × 2 mm inner- and outer eyelet 1.4571, 0,15 mm
WD39: WS 3860 2 × corrugated ring 1.4751, 3 × 2 mm outer eyelet 1.4571, 0,15 mm

WD39 design only available upward of dimension 220 × 320

All designs have the following TÜV-approvals:

• permissible operating overpressure p = 40 bar*
• permissible operating temperature T = 250 °C
• permissible cold water test overpressure p = 88 bar

*The upper value of the pressure limit of 40 bar does not result in the technical application limits of the sealing material/gasket system, but from the scope of the VdTÜV-information leaflets. Certain designs can also be used for temperatures up to 400 °C and pressures up to 100 bar [applicable for WS 3885, FD20 and FD30; WD 10, WD 30, WD 39] if installed professionally, with regard to sealing surfaces, correct dimensioning and assembly.

• Type tested according to VdTÜV-Instruction "Gaskets 100" [TRD 401 annex 1; test class D]
• Blow-out resistance
• Leakage reduction
• High compensation behaviour [design with corrugated ring]
• Prevents graphite erosion caused by the operating media [design with outer eyelet]
• Good handling
• No ageing in the range of permissible applications
• High chemical resistance
• No hardening at temperature
• No hardening elastomers, no hydrolysis sensitive fibers
• Cold water tight
• Immediately start-up tight, which means that permanent tightening is not necessary during start-up
• Can be used for the cold water pressure test - if they are not opened again
• A tight locking system is created in the cold water range, which reduces flange surface corrosion to a minimum
• Compensation behaviour of up to 3.0 mm depending on design
• Gaskets can be stored and used indefinitely.

The dimensions of oval gaskets are always defined by 4 dimension information and specified as follows: small inner oval [A] × large inner oval [B] × edge width [b] × thickness [t]

Oval elliptical shape

Oval stadium shape

Stocked standard dimensions [inner oval, elliptical in mm]; edge widths 15 mm or 25 mm:

Observation and hand hole gaskets [b = 15 mm]

80 × 120 mm | 100 × 150 mm | 115 × 165 mm | 120 × 160 mm | 150 × 200 mm

Head or manhole gaskets [b = 25 mm]

220 × 320 mm | 290x390 mm | 300 × 400 mm | 310 × 410 mm 320 × 420 mm | 350 × 450 mm

• Thicknesses depending on the gasket system: 3.0 mm, 4.0 mm, 5.0 mm or 8.0 mm
• Other dimensions upon request
• Delivered as complete sealing ring, individually packaged with assembly instruction