Lap Joint flange dimensions are covered in ASME B16.5 – which covers Pipe Flanges and Flanged Fittings for size NPS ½” to 24” for above NPS 26” to 60” it should be as per ASME B16.47.

During a dimensional inspection of a lap flange, you should check for

  • Outer & Inner Diameter of body
  • Bolt Circle & Bolt hole Diameter
  • Length of the Hub
  • Straightness and alignment of the bolt hole
lap joint flange dimensions

Class 150 Lap Joint Flange Dimensions

Size in InchSize in mmOuter DiameterFlange Thick.Lapped Thick.Lapped IDPCDLapped Thick.Lapped RadiusNo of BoltsBolt Size UNCMachine Bolt LengthRF Stud LengthHole SizeISO Stud SizeWeight in kg
ABCDEG
1/21590301622.960.311.2341/250555/8M140.8
3/420100381628.269.912.7341/250655/8M140.9
125110491734.979.414.3341/255655/8M140.9
1 1/432115592143.788.915.9541/255705/8M141.4
1 1/24012565225098.417.5641/265705/8M141.4
250150782562.5120.719.1845/870853/4M162.3
2 1/265180902975.4139.722.3845/875903/4M163.2
3801901083091.4152.423.91045/875903/4M163.7
3 1/29021512232104.1177.823.91185/875903/4M165
410023013533116.8190.523.91185/875903/4M165.9
512525516436144.4215.923.91183/485957/8M206.8
615028019240171.4241.325.41383/4851007/8M208.6
820034524644222.2298.528.61383/4901107/8M2013.7
1025040530549277.436230.213127/81001151M2419.5
1230048536556328.2431.831.813127/81001201M2429
1435053540079360.2476.335131211151351 1/8M2741
1640059545787411.2539.836.6131611151351 1/8M2754
1845063550597462.3577.939.713161 1/81251451 1/4M3059
20500700559103514.463542.913201 1/81401601 1/4M3075
24600815663111616749.347.913201 1/41501701 3/8M33100

Class 300 Lap Joint Flange Dimensions

Size in InchSize in mmOuter DiameterFlange Thick.Lapped Thick.Lapped IDPCDLapped Thick.Lapped RadiusNo of BoltsBolt Size UNCMachine Bolt LengthRF Stud LengthHole SizeISO Stud SizeWeight in kg
ABCDEG
1/21595382222.966.714.3341/255655/8M141.2
3/420115482528.282.615.9345/865753/4M161.4
125125542734.988.917.5345/865753/4M161.4
1 1/432135642743.798.419.1545/870853/4M161.8
1 1/240155703050114.320.7643/475907/8M202.7
250165843362.512722.3885/875903/4M163.2
2 1/2651901003875.4149.225.4883/4851007/8M204.6
3802101174391.4168.328.61083/4901107/8M205.9
3 1/29023013344104.1184.230.21183/4951107/8M207.7
410025514648116.820031.81183/4951157/8M2010
512528017851144.4235351183/41101207/8M2012.7
615032020652171.4269.936.613123/41101207/8M2017.7
820038026062222.2330.241.313127/81201401M2426
1025044532195277.4387.447.7131611401601 1/8M2736
12300520375102328.2450.850.813161 1/81451701 1/4M3052
14350585425111360.2514.45413201 1/81601801 1/4M3075
16400650483121411.2571.557.213201 1/41651901 3/8M3386
18450710533130462.3628.660.413241 1/41701951 3/8M33113
20500775587140514.4685.863.513241 1/41852051 3/8M33143
24600915702153616812.869.913241 1/22052301 5/8M39216
Piping Courses

Class 400 Lap Joint Flange Dimensions

Size in InchSize in mmOuter DiameterFlange Thick.Lapped Thick.Lapped IDPCDLapped Thick.Lapped RadiusNo of BoltsBolt Size UNCRF Stud LengthHole SizeISO Stud SizeWeight in kg
ABCDEG
1/21595382222.966.714.3341/2755/8M141.3
3/420115482528.282.615.9345/8903/4M161.5
125125542734.988.917.5345/8903/4M161.8
1 1/432135642943.798.420.7545/8953/4M162.3
1 1/240155703250114.322.3643/41107/8M203.2
250165843762.512725.4885/81103/4M164.1
2 1/2651901004175.4149.228.6883/41207/8M205.9
3802101174691.4168.331.81083/41257/8M207.3
3 1/29023013349104.1184.2351087/81401M249.6
410025514651116.8200351187/81401M2411.8
512528017854144.523538.11187/81451M2414.1
615032020657171.4269.941.313127/81501M2420
820038026068222.233047.7131211701 1/8M2731
10250445321102277.4387.45413161 1/81901 1/4M3042
12300520375108328.2450.857.213161 1/42051 3/8M3359
14350585425117360.2514.460.413201 1/42101 3/8M3382
16400650483127411.2571.563.513201 3/82201 1/2M36107
18450710533137462.3628.666.713241 3/82301 1/2M36130
20500775587146514.4685.869.913241 1/22401 3/4M39157
24600915702159616812.876.213241 3/42651 7/8M45232

Class 600 Lap Joint Flange Dimensions

Size in InchSize in mmOuter DiameterFlange Thick.Lapped Thick.Lapped IDPCDLapped Thick.Lapped RadiusNo of BoltsBolt Size UNCRF Stud LengthHole SizeISO Stud SizeWeight in kg
ABCDEG
1/21595382222.966.714.3341/2755/8M141.3
3/420115482528.282.615.9345/8903/4M161.4
125125542734.988.917.5345/8903/4M161.8
1 1/432135642943.798.420.7545/8953/4M162.3
1 1/240155703250114.322.3643/41107/8M203.2
250165843762.512725.4885/81103/4M164.1
2 1/2651901004175.4149.228.6883/41207/8M205.9
3802101174691.4168.331.81083/41257/8M207.3
3 1/29023013349104.1184.2351187/81401M249.6
410027515254116.8215.938.11187/81451M2416.8
512533018960144.4266.744.511811651 1/8M2729
615035522267171.4292.147.7131211701 1/8M2736
820042027376222.2349.255.613121 1/81901 1/4M3052
10250510343111277.4431.863.513161 1/42151 3/8M3377
12300560400117328.248966.713201 1/42201 3/8M3391
14350605432127360.252769.913201 3/82351 1/2M36105
16400685495140411.2603.276.213201 1/22551 5/8M39150
18450745546152462.365482.613201 5/82751 3/4M42182
20500815610165514.4723.988.913241 5/82851 3/4M42232
24600940718184616838.2101.613241 7/83302M48332

Class 900 Lap Joint Flange Dimensions

Size in InchSize in mmOuter DiameterFlange Thick.Lapped Thick.Lapped IDPCDLapped Thick.Lapped RadiusNo of BoltsBolt Size UNCRF Stud LengthHole SizeISO Stud SizeWeight in kg
ABCDEG
1/215120383222.982.622.3343/41107/8M201.8
3/420130443528.288.925.4343/41157/8M202.3
125150524134.9101.628.6347/81251M243.6
1 1/432160644143.7111.128.6547/81251M244.1
1 1/240180704450123.831.86411401 1/8M275.5
2502151055762.5165.138.1887/81451M2411.5
2 1/2652451246475.4190.541.38811601 1/8M2716.5
3802401275491.4190.538.11087/81451M2412
410029015970116.823544.51181 1/81701 1/4M3024
512535019079144.4279.450.81181 1/41901 3/8M3338
615038023586171.4317.555.613121 1/81901 1/4M3050
8200470298114222.2393.763.513121 3/82201 1/2M3678
10250545368127277.4469.969.913161 3/82351 1/2M36112
12300610419143328.2533.479.413201 3/82551 1/2M36148
14350640451156360.2558.885.813201 1/22751 5/8M39182
16400705508165411.261688.913201 5/82851 3/4M42193
18450785565190462.3685.8101.613201 7/83252M48258
20500855622210514.4749.3108132023502 1/8M52317
246001040749267616901.7139.713202 1/24402 5/8M64608

Class 1500 Lap Joint Flange Dimensions

Size in InchSize in mmOuter DiameterFlange Thick.Lapped Thick.Lapped IDPCDLapped Thick.Lapped RadiusNo of BoltsBolt Size UNCRF Stud LengthHole SizeISO Stud SizeWeight in kg
ABCDEG
1/215120383222.982.622.3343/41107/8M201.8
3/420130443528.288.925.4343/41157/8M202.3
125150524134.9101.628.6347/81251M243.7
1 1/432160644143.7111.128.6547/81251M244.1
1 1/240180704450123.831.86411401 1/8M275.5
2502151055762.5165.138.1887/81451M249.8
2 1/2652451246475.4190.541.38811601 1/8M2716.4
3802651337391.4203.247.71081 1/81801 1/4M3021.8
410031016290116.8241.3541181 1/41951 3/8M3333
5125375197105144.4292.173.11181 1/22501 5/8M3959
6150395229119171.4317.582.613121 3/82601 1/2M3675
8200485292143222.2393.792.113121 5/82901 3/4M42118
10250585368178277.4482.610813121 7/83352M48198
12300675451219328.2571.5123.9131623752 1/8M52264
14350750495241360.2635133.413162 1/44052 3/8M56341
16400825552260411.2704.8146.113162 1/24452 5/8M64454
18450915597276462.3774.716213162 3/44952 7/8M72590
20500985641292514.4831.8177.8131635403 1/8M76792
246001170762330616990.6203.213163 1/26153 5/8M901248

Class 2500 Lap Joint Flange Dimensions

Size in InchSize in mmOuter DiameterFlange Thick.Lapped Thick.Lapped IDPCDLapped Thick.Lapped RadiusNo of BoltsBolt Size UNCRF Stud LengthHole SizeISO Stud SizeWeight in kg
ABCDEG
1/215135434022.988.930.2343/41207/8M203.2
3/420140514328.295.231.8343/41257/8M203.7
125160574834.910835347/81401M245
1 1/432185735243.7130.238.15411501 1/8M277.5
1 1/24020579605014644.5641 1/81701 1/4M3010
250235957062.5171.450.98811801 1/8M2717.5
2 1/2652651147975.4196.857.2881 1/81951 1/4M3023
3803051339291.4228.666.71081 1/42201 3/8M3337.8
4100355165108116.827376.21181 1/22551 5/8M3957
5125420203130144.4323.892.11181 3/43001 7/8M4595
6150485235152171.4368.310813823452 1/8M52148
8200550305178222.2438.2127131223802 1/8M52221
10250675375229277.4539.8165.113122 1/24902 5/8M64425
12300760441254328.2619.1184.213122 3/45402 7/8M72500

Disclaimer –  Please check with ASME B16.5 Before using.

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