Flanged connection bolt length calculation

Key details about the DIN EN 1515 standard and related flange specifications:

• DIN EN 1515 specifies the dimensions of hexagon bolts and studs for use with flanged joints. It gives dimensions for bolt diameters M12 to M64.
• EN 10921 defines the requirements for steel flanges and flanged joints with PN (pressuretemperature rating) designations from PN 2.5 to PN 100. It covers multiple flange types like welding neck, slipon, socket weld, etc.
• The PN rating indicates the maximum allowable pressure in bar at a temperature of 20°C. Common ratings are PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100.
• For a given flange size and PN rating, EN 10921 specifies the required number of bolts and the bolt circle diameter. More bolts are required for higher PN ratings to handle the increased force.
• For example, a DN150 welding neck flange in PN10 requires 8 M20 bolts on a 190 mm bolt circle. The same flange in PN25 requires 12 M20 bolts on a 220 mm bolt circle.
• The bolts are used to join the mating flanges together. Hexagon head bolts are most common, along with stud bolts in some high temperature applications. The bolt length depends on the flange and gasket thickness.

So in summary, DIN EN 1515 provides bolt dimensions, EN 10921 defines flange specs and required bolt sizes/numbers for different PN ratings. These standards help ensure safe reliably flanged joints.

General Standards
DIN EN 15151	Flanges and their joints Bolting Part 1: Selection of bolting	Jan00
DIN EN 15152	Flanges and their joints Bolting Part 2: Classification of bolt materials for steel flanges, PN designated	Mar02
DIN EN 15153	Flanges and their joints Bolting Part 3: Classification of bolt materials for steel flanges, Class designated	Dec05
DIN EN 15154	Flanges and their joints Bolting Part 4: Selection of bolting for equipment subject to the Pressure Equipment Directive 2014/68/EU	Dec22
DIN EN 15911	Flanges and their joints Design rules for gasketed circular flange connections Part 1: Calculation	Apr14
DIN EN 15911 Beiblat 1	Flanges and their joints Design rules for gasketed circular flange connections Background information	Oct01
DIN EN 15912	Flanges and their joints Design rules for gasketed circular flange connections Part 2: Gasket Parameters	Sep08
DIN CEN/TS 15913	Flanges and their joints Design rules for gasketed circular flange connections Part 3: Calculation method for metal to metal contact type flanged joint	Oct07
DIN EN 15914	Flanges and their joints Part 4: Qualification of personnel competency in the assembly of the bolted connections of critical service pressurized systems	Dec13
Materials&Mechanical Properties
DIN EN 10269	Steels and nickel alloys for fasteners with specified elevated and/or low temperature properties	Feb14
DIN EN ISO 8981	Mechanical properties of fasteners made of carbon steel and alloy steel Part 1: Bolts, screws and studs with specified property classes Coarse thread and fine pitch thread (ISO 8981:2013)	May13
DIN EN ISO 8982	Fasteners Mechanical properties of fasteners made of carbon steel and alloy steel Part 2: Nuts with specified property classes (ISO 8982:2022)	Feb23
DIN EN ISO 8983	Fasteners Mechanical properties of fasteners made of carbon steel and alloy steel Part 3: Flat washers with specified property classes (ISO 8983:2018 + Amd 1:2020)	Nov21
Flanges
DIN EN 10921	Flanges and their joints Circular flanges for pipes, valves, fittings and accessories, PN designated Part 1: Steel flanges	Dec18
DIN EN 10922	Flanges and their joints Circular flanges for pipes, valves, fittings and accessories, PN designated Part 2: Cast iron flanges	Jun97
DIN EN 10923	Flanges and their joints Circular flanges for pipes, valves, fittings and accessories, PN designated Part 3: Copper alloy flanges	Oct04
DIN EN 10924	Flanges and their joints Circular flanges for pipes, valves, fittings and accessories, PN designated Part 4: Aluminium alloy flanges	Aug02
Gaskets
DIN EN 15141	Flanges and their joints Dimensions of gaskets for PNdesignated flanges Part 1: Nonmetallic flat gaskets with or without inserts	Aug97
DIN EN 15142	Flanges and their joints Gaskets for PNdesignated flanges Part 2: Spiral wound gaskets for use with steel flanges	Mar21
DIN EN 15143	Flanges and their joints Dimensions of gaskets for PNdesignated flanges Part 3: Nonmetallic PTFE envelope gaskets	Aug97
DIN EN 15144	Flanges and their joints Dimensions of gaskets for PNdesignated flanges Part 4: Corrugated flat or grooved metallic and filled metallic gaskets for use with steel flanges	Aug97
DIN EN 15146	Flanges and their joints Dimensions of gaskets for PNdesignated flanges Part 6: Covered serrated metal gaskets for use with steel flanges	Mar04
DIN EN 15147	Flanges and their joints Gaskets for PNdesignated flanges Part 7: Covered metal jacketed gaskets for use with steel flanges	Aug04
DIN EN 15148	Flanges and their joints Dimensions of gaskets for PNdesignated flanges Part 8: Polymeric ORing gaskets for grooved flanges	Feb05
Bolts
DIN EN ISO 4014	Fasteners  Hexagon head bolts  Product grades A and B (ISO 4014:2022)	Oct22
DIN EN ISO 4016	Fasteners Hexagon head bolts Product grade C (ISO 4016:2022)	Oct22
DIN EN ISO 4017	Fasteners Hexagon head screws Product grades A and B (ISO 4017:2022)	Oct22
DIN EN ISO 4018	Fasteners Hexagon head screws Product grade C (ISO 4018:2022)	Oct22
Studs
DIN 939	Studs Metal end ≈ 1.25d	Feb95
Nuts
DIN EN ISO 4032	Hexagon regular nuts (style 1) Product grades A and B (ISO 4032:2012)	Apr13
DIN EN ISO 4034	Hexagon regular nuts (style 1) Product grade C (ISO 4034:2012)	Apr13
Washers
DIN EN ISO 7089	Plain washers Normal series, Product grade A (ISO 7089:2000)	Nov00
DIN EN ISO 7091	Plain washers Normal series Product grade C (ISO 7091:2000)	Apr19