6 4.2 Qmin[L], QSmin[L] Qmin[L] is the minimum gasket surface pressure on assembly required at ambient temperature in order to seat the gasket into the flange facing roughness and close
General
The data presented in the following tables is intended solely for preliminary calculations using EN 1591-1, derived from test methods outlined in EN 13555 This data reflects a selection of various commercial gasket styles and makes available in Europe For final calculations, users of EN 1591-1 should consult their chosen gasket supplier to obtain specific data regarding the style and thickness of the gasket they plan to use.
A group of end users has derived a pre-calculation method of use of EN 1591-1 that allows gasket selection without any further calculation This is outlined in Annex C
EN 13555 permits the testing of gaskets sized for either DN40/PN40 or NPS 4 CLASS 300 flanges All the data values given in this document were obtained from DN40/PN 40 gaskets
The EN 13555 standards for Q Smax have been followed, indicating that if no collapse occurs during the Q Smax test, the Q Smax value is determined by the highest surface pressure, Q i, recorded during the P QR test.
The tables present data organized into three groups of gasket parameters: Q min[L] and Q Smin[L] in section 4.2, followed by Q Smax and P QR in section 4.3, and E G in section 4.4 This structure facilitates an easy understanding of how each parameter varies with gasket type Each section begins with a brief explanation of the parameters included For additional details on gasket parameters or testing methods, refer to EN 13555.
To ensure the safety and tightness of a flanged joint, data generated according to EN 13555 should be utilized alongside EN 1591-1 Since it is impractical to tabulate gasket parameters for every possible value of the controlling parameters, it is advisable to use results from the next "worse" values to maintain a conservative outcome.
The parameters derived from gaskets through the tests outlined in EN 13555 are interconnected in intricate ways, and the following guidance may appear simplistic considering these complex inter-relationships.
For optimal sealing solutions, it is advisable to consult preferred suppliers or manufacturers, as they can offer essential guidance to assist in the selection process.
Q Smin[L] is influenced by Q A , the higher the level of Q A achieved on assembly the better
Q A will be limited by either the maximum bolt load available, the maximum flange loading that can be permitted or the maximum gasket loading, Q Smax , that can be withstood
High values of Q Smax are preferred If the Q Smax value is not available for the specific temperature and gasket thickness required, it is advisable to use the Q Smax value from the next higher available options.
For secure achievement of a given level of tightness, L , the lower the values of Q min[L] and Q Smin[L] the better
Interpolation is allowed when data is available for multiple helium pressures, enabling the estimation of values for the desired pressure If data for the specific thickness of interest is unavailable, it is advisable to use data from the next higher available thickness.
Desirable outcomes include low values of Q min[L] and Q Smin[L], as well as a minimal difference between successive Q Smin[L] values This low difference signifies reduced sensitivity to off-loading during service.
For gasket types, achieving high P QR values is essential If the desired P QR value is not available for the specific temperature, stiffness, and surface pressure required, it is advisable to use the P QR value from the next higher level.
Desirable low values of E G are essential If the specific E G value is not available for the exact temperature, surface pressure, and thickness needed, it is recommended to use the E G value from the next higher level.
The data presented in the tables was generated during the evolution of the test methods outlined in EN 13555 Consequently, some gasket test data does not fully comply with the subsequently established rules in EN 13555 For example, in the 4.3 set of tables, P QR values are only provided for a stiffness of 500 kN/mm, whereas the standard requires P QR values to be determined across a range of stiffness levels.
The notes at the end of the 4.3 set of tables of Q Smax and P QR give important guidance in the use of the data in that set of tables
For relation between the gasket types and the codes used in the tables see Annex A
Q min[L] , Q Smin[L]
The minimum gasket surface pressure, denoted as Q min[L], is essential for ensuring proper gasket seating against flange facing roughness at ambient temperature This pressure is crucial for sealing internal leakage channels, thereby achieving the necessary tightness class L for the internal test pressure.
Q Smin[L] represents the minimum gasket surface pressure necessary to maintain the required tightness class L under service pressure conditions, specifically after unloading and at the service temperature The values provided in Tables 2 to 15 are exclusively for ambient temperature conditions.
L is defined in terms of specific leakage rates in Table 1 Additional better tightness classes are introduced as required by continuing the series
Tightness Class Specific Leakage Rate mg/(sm)
For the Tables 2 to 15 the following marking applies:
Q min[L] or Q Smin[L] values for 40 bar without underlining;
Q min[L] or Q Smin[L] figures for 10 bar are marked by a dashed line;
Q min[L] or Q Smin[L] figures for 80 bar are underlined;
Q min[L] or Q Smin[L] figures for 160 bar are double underlined
Table 2 — Graphite filled spiral wound gasket with outer ring
Q min[L], Q Smin[L] for 40 bar of helium, plus some data for other pressures, at ambient temperature
Table 3 — Graphite filled spiral wound gasket with outer and inner ring
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 4 — Low stress, graphite filled, spiral wound gasket with outer and inner rings
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 5 — PTFE filled spiral wound gasket with outer and inner rings
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 6 — Corrugated metal core with graphite facing
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 7 — Metal jacketed gasket with graphite filler
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 8 — Graphite covered metal jacketed gasket with graphite filler and outer ring
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 9 — Graphite sheet with multiple thin metal insertions
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 10 — Graphite sheet with tanged stainless steel core
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 11 — Serrated metal core (Kammprofile) with graphite facing
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Code G02, 2,0 mm Code D01, 2,0 mm Code A02, 2,0 mm Code K02, 2,0 mm
Table 13 — Non-asbestos, fibre based sheet
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature,
Code 1-9-101-1, 2 mm Code G01, 2 mm Code E01, 2,1 mm Code D02, 1,9 mm Code B01, 2 mm
Table 14 — Proprietary type of graphite faced Kammprofile with secondary metal to metal seal
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Table 15 — Proprietary PTFE/graphite gasket with metal eyelet
Q min[L], Q Smin[L] for 40 bar of helium , plus some data for other pressures, at ambient temperature
Q smax and P QR
Q smax represents the highest surface pressure that can be applied to a gasket at a specified temperature without causing collapse or compressive failure P QR is a factor that accounts for the impact of load relaxation on the gasket, occurring between the initial bolt-up and after prolonged exposure to service temperatures.
Table 16 — Q smax and P QR (EN 13555 based data)
Q Smax P QR ( Q i ) for connection stiffness, Q i in MPa, of
Material code, initial gasket thickness
Non-asbestos fibre based sheet
Q smax P QR ( Q i ) for connection stiffness, Q i in MPa, of
Material code, initial gasket thickness
Serrated metal core [Kammprofile] with graphite facing
Graphite sheet with tanged stainless steel core
Q smax P QR ( Q i ) for connection stiffness, Q i in MPa, of
Material code, initial gasket thickness
Graphite sheet with multiple thin metal insertions
Graphite covered metal jacketed with graphite filler and outer ring
Metal jacketed with graphite filler
Q smax P QR ( Q i ) for connection stiffness, Q i in MPa, of
Material code, initial gasket thickness
Corrugated metal core with graphite facing
PTFE filled spiral wound gasket with both inner and outer rings
Low Stress , graphite filled, spiral wound gasket with both inner & outer rings
Graphite filled spiral wound gasket with outer ring only
Graphite filled spiral wound gasket with both inner and outer rings
Proprietary PTFE / Graphite gasket with metal eyelet
Users must exercise caution when utilizing the Q Smax values listed above, as factors such as gasket thickness, land width, flange surface finish, and other variables significantly affect the Q Smax value during operation.
In some instances in the above the Q Smax value was set by the gasket supplier at a more conservative level than that indicated by the test method given in EN 13555
Two distinct philosophies guide the application of spiral wound gaskets For PN designated flanges, metal-to-metal contact between the flange faces and the outer guide ring of the spiral is prohibited In contrast, for Class designated flanges, it is standard practice to compress the gasket until contact occurs As a result, the Q Smax values differ based on these practices.
E G
E G is the unloading modulus determined from the thickness recovery of the gasket between the initial surface pressure and unloading to a third of this initial surface pressure
Table 17 — Graphite filled spiral wound gasket with outer ring
Table 18 — Graphite filled spiral wound gasket with inner and outer rings
Table 19 — Low stress, graphite filled, spiral wound gasket with inner and outer rings
Table 20 — PTFE filled spiral wound gasket with inner and outer rings
Table 21 — Corrugated metal core with graphite facing
3,2 mm 2,3 mm eyelets 2,3 mm eyelets 3,2 mm 2,3 mm eyelets 3,2 mm
Table 22 — Metal jacketed with graphite filler
3,2 mm 3,6 mm 3,2 mm 3,6 mm 3,6 mm 3,2 mm
Table 23 — Graphite sheet with multiple thin metal insertions
Table 24 — Graphite sheet with tanged stainless steel core
2,1 mm 2 mm 2 mm 2,1 mm 2 mm 2,1 mm 2 mm
Table 25 — Serrated metal core [Kammprofile] with graphite facing
2 mm 2 mm 2,0 mm 2,0 mm 2,0 mm 2,0 mm 2,0 mm 2,0 mm 2,0 mm 2,0 mm
2 mm 2 mm 2 mm 2 mm 2,0 mm 2,0 mm 2,0 mm 2,0 mm
Table 27 — Non-Asbestos fibre based sheet
2,0 mm 2,1 mm 1,9 mm 2,0 mm 2 mm 2,0 mm 2,1 mm 1,9 mm 2,0 mm 2 mm
2,0 mm 2,1 mm 1,9 mm 2,0 mm 2 mm
Table 28 — Proprietary type of graphite faced kammprofile with secondary metal to metal seal
Table 29 — Graphite covered metal jacketed with graphite filler and outer ring
4,8 mm 4,5 mm 4,8 mm 4,5 mm 4,8 mm 4,5 mm
Table 30 — Proprietary PTFE/Graphite gasket with metal eyelet
Relation between the gasket types and the codes used in the tables
Table A.1 — Relation between the gasket types and the different codes
Description Form Design Structure Extra rings Reinforcement or filler
Sheet generic PTFE, modified none — 1-10-102-1
Proprietary PTFE / Graphite gasket with metal eyelet metal eyelet PTFE / Graphite PTFE / Graphite K01
Jacketed generic metal jacket graphite — 6-4-103-1
Metal jacketed with graphite filler
Graphite covered metal jacketed with graphite filler & outer ring
Serrated metal core [kammprofile] with graphite facing Serrated
Serrated (kammprofil) proprietary metal — graphite, metal to metal seal
Proprietary type of graphite faced kammprofile with secondary metal to metal seal
Corrugated proprietary metal stainless steel eyelets
Sheet generic graphite tanged stainless steel
Graphite sheet with tanged stainless steel core
Gasket type Materials Code Description Form Design Structure Extra rings Reinforcement or filler
Facing CETIM 2) MPA 3) generic non- asbestos, “it” calendered none — G01
— 1-9-101-1 generic non- asbestos, “it” calendered, reduced binder content
Non-asbestos, fibre based sheet
Sheet proprietary non- asbestos, non-woven fabric, impregnated
Graphite sheet with multiple thin metal insertions Sheet proprietary graphite multiple thin metal insertions
PTFE filled spiral wound gasket with both outer and inner rings
Spiral-wound generic metallic winding inner, outer PTFE — G03
Public sources of reliable data
Access the online database of EN 13555 data at www.gasketdata.org, established by Fachhochschule Münster This resource exclusively includes data collected in strict compliance with established requirements.
EN 13555 and subject to random verification checks
Outline of a pre-calculation method of gasket selection
End users recognized that employing EN 1591-1 for flange calculations would lead to a significant number of ongoing calculations, prompting their desire to discover methods to eliminate the need for repetitive computations.
For sites utilizing flanges of a specific standard and requiring uniform sealing levels, pre-calculations allow for the selection of gaskets without additional calculations This approach ensures that only gaskets with parameters within defined limits are utilized, streamlining the process and enhancing efficiency.
Accordingly, they found for Flange Type 11 in the latest version of EN 1092-1 that a leakage rate of 0,1 mg/(s⋅m) or lower would be achieved if a gasket having :
Q min[0,1] of 25 MPa (EN 1514-1 gasket) or 50 MPa (EN 1514-2 gasket) or less,
Q Smax of 100 MPa (EN 1514-1 gasket) or 300 MPa (EN 1514-2 gasket) or more,
E G of E G = 20 MPaãQ I + 8 000 MPa (EN 1514-1 gasket) or E G = 20 MPaãQ I + 10 000 MPa (EN 1514-2 gasket) or less,
P QR such that the following equation is fulfilled: Q Smin[L]/Q A ≤ P QR,
and Q Smin[0,1] of 6,6 MPa or less
NOTE 1 As in EN 13555, values below 10 MPa for Q Smin[L] and Q min[L] are not measured, and one can extrapolate down to Q Smin[0,1] of 6,6 MPa
This method can be directly applied to any gaskets outlined in the EN 1514 series of standards Additionally, with the repetition of the necessary background work, it can also be utilized for the EN 12560 series or any other dimensional standard.
[1] www.europeansealing.com (on-line reference)
[2] www.gasketdata.org (on-line reference)