EN 13555

EN 13555 provides the test method for generating the gasket parameters used in EN 1591-1 calculations. 

Gasket Constant Definitions

PQR A measure of creep relaxation at a predefined temperature. It is the ratio between the gasket stress after relaxation and the initial gasket stress. The ideal PQR value is 1. The closer the test value is to the ideal value, the lower the loss of gasket stress.
Qmin(L) The minimum required gasket stress at ambient temperature for a certain leakage class L when the seal is first installed.
QSmin(L) The minimum required gasket stress for a certain leakage class L in service.
QSmax The maximum gasket stress that may be applied on the gasket, without damage or intrusion into the bore, at the indicated temperatures. It depends on the temperature and the gasket thickness.
EG The recovery (elastic behavior) of a seal at load reduction and is related to the modulus of elasticity. It depends on the applied gasket stress, the seal thickness and the temperature.

 

General Test Method Description

PQR Creep Relaxation is measured at different temperatures, initial gasket stress, seal thickness values and flange stiffness values. The seal initially is exposed to the predefined gasket stress, then the temperature is increased and maintained for four hours. The residual gasket stress is then measured.
Qmin;
QSmin		 A load is applied to and removed from the seal in predefined increments, with the leakage being measured constantly. The internal pressure is usually 40 bar (test gas: helium).
QSmax;
EG

The gasket stress is increased cyclically and then reduced to 1/3 of the previous gasket stress. The seal thickness is then measured. The test is repeated at various temperatures.


The EG value is calculated from the load reductions and thickness changes. For QSmax, a sudden drop in seal thickness indicates failure. If a sudden drop occurs, the value of the loading step before failure is taken. In case no failure occurs, the maximum possible gasket stress of the test equipment is taken. The identified value is then used as the initial stress in a PQR test to verify the final QSmax under constant loading.

Test Results

Please find below the test results by tape thickness.

Note: If the gasket thickness is not directly listed above, use the data from the next higher thickness.

m&y

m & y are gasket constants used for flange design as specified in the ASME Boiler and Pressure Vessel Research Code Division 1 Section VIII Appendix 2. Leak Rates versus Y stresses and m factor for Gaskets is currently being proposed as a new test method in the ASTM F03 Working Group.

Gasket Constant Definitions

m, maintenance factor, is a factor that describes the amount of additional preload required to maintain the compressive load on a gasket after internal pressure is applied to a joint. 

y, seating stress, is the minimum compressive stress (psi) required to achieve an initial seal.

Test Results

Because GORE® Universal Pipe Gasket (Style 800) can be used in a wide range of applications, Gore wanted to ensure m&y values were applicable to each application type. Therefore, Gore modified the archived m&y test protocol to account for the influence of internal pressure and desired sealability. The values below reflect a T3 seal as tested per CETIM, reference report no. 774630/6J1/a.

Flange Type Plastic/FRP Glass-lined Steel Steel
Maximum Internal Pressure (psi) 290 580 580
m 2.5 1.4 2.4
y (psi) 290 725 1,500

AD 2000 B 7

There are no specific test standards for AD 2000 B 7 Gasket Parameters. However, an estimation is provided below. The 2015 edition of "AD 2000-Merkblatt B 7" refers to EN 13555 as a test standard(1) and uses table 9 from VDI 2200(2) for the conversion method. Please note that VDI 2200 states that such a conversion is invalid due to the different measurement methods. "Only the method according to DIN EN 1591-1 and AD 2000 in conjunction with DIN EN 1591-1 and FE analysis can be used for providing stability, leak tightness and TA Luft proof."(3)

Gore supports the use of the AD 2000-Merkblatt B 7 and provides the necessary gasket parameters below.

There are the following relations(1):

k0KD ≙ Qmin · bD
k1 ≙ (QSmin / p) · bD since m ≙ (QSmin / p)(4)
k0KDϑ ≙ QSmax · bD

where,

Qmin minimum required gasket stress at ambient temperature when the seal is first installed (based on EN 13555)
QSmin minimum required gasket stress in service (based on EN 13555)
QSmax maximum gasket stress that may be applied on the gasket at an indicated temperature ϑ (based on EN 13555)
bD width of the gasket
p internal pressure of the media
k1 AD 2000 B 7 gasket parameter for service condition
k0KD AD 2000 B 7 gasket parameter for gasket deformation

For GORE Universal Pipe Gasket (Style 800) in 3 mm thickness and with an internal pressure of 40 bar (580 psi), this results in:

  • k1 = 1.25 · bD
  • k0KD = 5 MPa · bD
  • k0KDϑ = 80 MPa · bD temperature ϑ = 230°C (446°F)

If necessary for a specific application, Gore recommends to do individual conversions based on data from EN 13555.

The use of the general values given in table 1 of AD 2000-Merkblatt B 7(5) is not broadly recommended. However they may be applicable depending on the given situation.

Please also note that the quoted standards of DIN 2690 to DIN 2692 were superseded by EN 1514-1 in 1997.

(1)Arbeitsgemeinschaft Druckbehälter: AD 2000-Merkblatt B 7, Berechnung von Druckbehältern, Schrauben, Seite 4, 7.1.2.4, April 2015.
(2)Verein Deutscher Ingenieure e. V.: VDI 2200, Tight flange connections - Selection, calculation, design and assembly of bolted flange connections, page 36, table 9, June 2007.
(3)Verein Deutscher Ingenieure e. V.: VDI 2290, Emission Control - Sealing constants for flange connections, page 8, June 2012.
(4)Please note that factor m = QSmin / p was defined by DIN V 2505 which was superseded by EN 1591-1 where m is no longer used.
(5)Arbeitsgemeinschaft Druckbehälter: AD 2000-Merkblatt B 7, Berechnung von Druckbehältern, Schrauben, Seite 6, Tabelle 1, April 2015.

Residents of some states have the right to opt-out of the “sharing” or “selling” of their personal information. Gore does not "sell" the personal information of website users. Gore may "share" the personal information of website users, as standard advertising practice meant to offer you a more personalized service.

If you want to opt-out from Gore “sharing” your personal information, click on Opt-Out of Sharing to turn off the targeting cookies that we share with our advertising partners in order to provide you with personalized information. Disabling sharing will stop the use of cookies to targeted advertising but you may still see generic Gore ads.

Please note that your exercising of the rights outlined will have no adverse effect on the price and quality of our goods or services.

Opt-Out of Sharing

You Have Successfully Opted Out of the Sharing of Your Personal Information

Please note that if you clear your cookies and then use another device or browser, etc. your opt-out status is not transferred to the new device or browser.

Top