Lap Joint Flange Sizes (ASME B16.5)

Quick Reference

ASME B16.5 lap joint flange dimensions (NPS 1/2” to 24”) for Classes 150-2500. Used with stub ends-allows carbon steel flange with stainless/alloy stub end for cost savings. Rotates freely for bolt alignment.

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ASME Lap-Joint Flange Dimensions and Weights

The tables below show ASME B16.5 lap-joint flange dimensions including: inside diameter (ID), outside diameter (OD), bolt circle, flange thickness, and bolt hole specifications.

Lap-Joint Flanges Sizes in Inches

Lap-Joint Class 150

Lap-joint flange dimensions for Class 150 per ASME B16.5 (in inches). Includes OD, ID, bolt circle, thickness, and bolt hole specifications.

FLANGENPS	InsideDiameter	OutsideDiameter	Bolt Circle (BC)	H	T1	T2	RA	Bolt Hole (B)	No. of Bolt Holes
1/2″	0.88″	3.50″	2.38″	1.19″	.44″	.62″	.12″	.62″	4
3/4″	1.09″	3.88″	2.75″	1.50″	.50″	.62″	.12″	.62″	4
1″	1.36″	4.25″	3.12″	1.94″	.56″	.69″	.12″	.62″	4
1-1/4″	1.70″	4.62″	3.50″	2.31″	.62″	.81″	.19″	.62″	4
1-1/2″	1.97″	5.00″	3.88″	2.56″	.69″	.88″	.25″	.62″	4
2″	2.44″	6.00″	4.75″	3.06″	.75″	1.00″	.31″	.75″	4
2-1/2″	2.94″	7.00″	5.50″	3.56″	.88″	1.12″	.31″	.75″	4
3″	3.57″	7.50″	6.00″	4.25″	.94″	1.19″	.38″	.75″	4
3-1/2″	4.07″	8.50″	7.00″	4.81″	.94″	1.25″	.38″	.75″	8
4″	4.57″	9.00″	7.50″	5.31″	.94″	1.31″	.44″	.75″	8
5″	5.66″	10.00″	8.50″	6.44″	.94″	1.44″	.44″	.88″	8
6″	6.72″	11.00″	9.50″	7.56″	1.00″	1.56″	.50″	.88″	8
8″	8.72″	13.50″	11.75″	9.69″	1.12″	1.75″	.50″	.88″	8
10″	10.88″	16.00″	14.25″	12.00″	1.19″	1.94″	.50″	1.00″	12
12″	12.88″	19.00″	17.00″	14.38″	1.25″	2.19″	.50″	1.00″	12
14″	14.14″	21.00″	18.75″	15.75″	1.38″	3.12″	.50″	1.12″	12
16″	16.16″	23.50″	21.25″	18.00″	1.44″	3.44″	.50″	1.12″	16
18″	18.18″	25.00″	22.75″	19.88″	1.56″	3.81″	.50″	1.25″	16
20″	20.20″	27.50″	25.00″	22.00″	1.69″	4.06″	.50″	1.25″	20
22″	22.22″	29.50″	27.25″	24.25″	1.81″	4.25″	.50″	1.38″	20
24″	24.25″	32.00″	29.50″	26.12″	1.88″	4.38″	.50″	1.38″	20

Lap-Joint Class 300

Lap joint flange dimensions class 300 in inches (ASME B16.5)

FLANGENPS	InsideDiameter	OutsideDiameter	Bolt Circle (BC)	H	T1	T2	RA	Bolt Hole (B)	No. of Bolt Holes
1/2″	0.90″	3.75″	2.62″	1.50″	0.56″	0.88″	.12″	0.62″	4
3/4″	1.11″	4.62″	3.25″	1.88″	0.62″	1.00″	.12″	0.75″	4
1″	1.38″	4.88″	3.50″	2.12″	0.69″	1.06″	.12″	0.75″	4
1-1/4″	1.72″	5.25″	3.88″	2.50″	0.75″	1.06″	.19″	0.75″	4
1-1/2″	1.97″	6.12″	4.50″	2.75″	0.81″	1.19″	.25″	0.88″	4
2″	2.46″	6.50″	5.00″	3.31″	0.88″	1.31″	.31″	0.75″	8
2-1/2″	2.97″	7.50″	5.88″	3.94″	1.00″	1.50″	.31″	0.88″	8
3″	3.60″	8.25″	6.62″	4.62″	1.12″	1.69″	.38″	0.88″	8
3-1/2″	4.10″	9.00″	7.25″	5.25″	1.19″	1.75″	.38″	0.88″	8
4″	4.60″	10.00″	7.88″	5.75″	1.25″	1.88″	.44″	0.88″	8
5″	5.69″	11.00″	9.25″	7.00″	1.38″	2.00″	.44″	0.88″	8
6″	6.75″	12.50″	10.62″	8.12″	1.44″	2.06″	.50″	0.88″	12
8″	8.75″	15.00″	13.00″	10.25″	1.62″	2.44″	.50″	1.00″	12
10″	10.92″	17.50″	15.25″	12.62″	1.88″	3.75″	.50″	1.12″	16
12″	12.92″	20.50″	17.75″	14.75″	2.00″	4.00″	.50″	1.25″	16
14″	14.18″	23.00″	20.25″	16.75″	2.12″	4.38″	.50″	1.25″	20
16″	16.19″	25.50″	22.50″	19.00″	2.25″	4.75″	.50″	1.38″	20
18″	18.20″	28.00″	24.75″	21.00″	2.38″	5.12″	.50″	1.38″	24
20″	20.25″	30.50″	27.00″	23.12″	2.50″	5.50″	.50″	1.38″	24
22″	22.25″	33.00″	29.25″	25.25″	2.63″	5.75″	.50″	1.63″	24
24″	24.25″	36.00″	32.00″	27.62″	2.75″	6.00″	.50″	1.62″	24

Lap-Joint Class 400

Lap joint flange dimensions class 400 in inches (ASME B16.5)

FLANGENPS	InsideDiameter	OutsideDiameter	Bolt Circle (BC)	H	T1	T2	RA	Bolt Hole (B)	No. of Bolt Holes
1/2″	0.90″	3.75″	2.62″	1.50″	0.56″	0.88″	.12″	0.62″	4
3/4″	1.11″	4.62″	3.25″	1.88″	0.62″	1.00″	.12″	0.75″	4
1″	1.38″	4.88″	3.50″	2.12″	0.69″	1.06″	.12″	0.75″	4
1-1/4″	1.72″	5.25″	3.88″	2.50″	0.81″	1.12″	.19″	0.75″	4
1-1/2″	1.97″	6.12″	4.50″	2.75″	0.88″	1.25″	.25″	0.88″	4
2″	2.46″	6.50″	5.00″	3.31″	1.00″	1.44″	.31″	0.75″	8
2-1/2″	2.97″	7.50″	5.88″	3.94″	1.12″	1.62″	.31″	0.88″	8
3″	3.60″	8.25″	6.62″	4.62″	1.25″	1.81″	.38″	0.88″	8
3-1/2″	4.10″	9.00″	7.25″	5.25″	1.38″	1.94″	.38″	1.00″	8
4″	4.60″	10.00″	7.88″	5.75″	1.38″	2.00″	.44″	1.00″	8
5″	5.69″	11.00″	9.25″	7.00″	1.50″	2.12″	.44″	1.00″	8
6″	6.75″	12.50″	10.62″	8.12″	1.62″	2.25″	.50″	1.00″	12
8″	8.75″	15.00″	13.00″	10.25″	1.88″	2.69″	.50″	1.12″	12
10″	10.92″	17.50″	15.25″	12.62″	2.12″	4.00″	.50″	1.25″	16
12″	12.92″	20.50″	17.75″	14.75″	2.25″	4.25″	.50″	1.38″	16
14″	14.18″	23.00″	20.25″	16.75″	2.38″	4.62″	.50″	1.38″	20
16″	16.19″	25.50″	22.50″	19.00″	2.50″	5.00″	.50″	1.50″	20
18″	18.20″	28.00″	24.75″	21.00″	2.62″	5.38″	.50″	1.50″	24
20″	20.25″	30.50″	27.00″	23.12″	2.75″	5.75″	.50″	1.62″	24
22″	22.25″	33.00″	29.25″	25.25″	2.88″	6.00″	.50″	1.75″	24
24″	24.25″	36.00″	32.00″	27.62″	3.00″	6.25″	.50″	1.88″	24

Lap-Joint Class 600

Lap joint flange dimensions class 600 in inches (ASME B16.5)

FLANGENPS	InsideDiameter	OutsideDiameter	Bolt Circle (BC)	H	T1	T2	RA	Bolt Hole (B)	No. of Bolt Holes
1/2″	0.90″	3.75″	2.62″	1.50″	0.56″	0.88″	.12″	0.62″	4
3/4″	1.11″	4.62″	3.25″	1.88″	0.62″	1.00″	.12″	0.75″	4
1″	1.38″	4.88″	3.50″	2.12″	0.69″	1.06″	.12″	0.75″	4
1-1/4″	1.72″	5.25″	3.88″	2.50″	0.81″	1.12″	.19″	0.75″	4
1-1/2″	1.97″	6.12″	4.50″	2.75″	0.88″	1.25″	.25″	0.88″	4
2″	2.46″	6.50″	5.00″	3.31″	1.00″	1.44″	.31″	0.75″	8
2-1/2″	2.97″	7.50″	5.88″	3.94″	1.12″	1.62″	.31″	0.88″	8
3″	3.60″	8.25″	6.62″	4.62″	1.25″	1.81″	.38″	0.88″	8
3-1/2″	4.10″	9.00″	7.25″	5.25″	1.38″	1.94″	.38″	1.00″	8
4″	4.60″	10.75″	8.50″	6.00″	1.5″	2.12″	.44″	1.00″	8
5″	5.69″	13.00″	10.50″	7.44″	1.75″	2.38″	.44″	1.12″	8
6″	6.75″	14.00″	11.50″	8.75″	1.88″	2.62″	.50″	1.12″	12
8″	8.75″	16.50″	13.75″	10.75″	2.19″	3.00″	.50″	1.25″	12
10″	10.92″	20.00″	17.00″	13.5″	2.50″	4.38″	.50″	1.38″	16
12″	12.92″	22.00″	19.25″	15.75″	2.62″	4.62″	.50″	1.38″	20
14″	14.18″	23.75″	20.75″	17.00″	2.75″	5.00″	.50″	1.50″	20
16″	16.19″	27.00″	23.75″	19.50″	3.00″	5.50″	.50″	1.62″	20
18″	18.20″	29.25″	25.75″	21.50″	3.25″	6.00″	.50″	1.75″	20
20″	20.25″	32.00″	28.50″	24.00″	3.50″	6.50″	.50″	1.75″	24
22″	22.25″	34.25″	30.63″	26.25″	3.75″	6.88″	.50″	1.75″	24
24″	24.25″	37.00″	33.00″	28.25″	4.00″	7.25″	.50″	2.00″	24

Lap-Joint Class 900

Lap joint flange dimensions class 900 in inches (ASME B16.5)

FLANGENPS	InsideDiameter	OutsideDiameter	Bolt Circle (BC)	H	T1	T2	RA	Bolt Hole (B)	No. of Bolt Holes
3″	3.60″	9.50″	7.50″	5.00″	1.50″	2.13″	.38″	1.00″	8
4″	4.60″	11.50″	9.25″	6.25″	1.75″	2.75″	.44″	1.25″	8
5″	5.69″	13.75″	11.00″	7.50″	3.00″	3.13″	.44″	1.38″	8
6″	6.75″	15.00″	12.50″	9.25″	2.19″	3.38″	.50″	1.25″	12
8″	8.75″	18.50″	15.50″	11.75″	2.50″	4.50″	.50″	1.50″	12
10″	10.92″	21.50″	18.50″	14.50″	2.75″	5.00″	.50″	1.50″	16
12″	12.92″	24.00″	21.00″	16.50″	3.13″	5.63″	.50″	1.50″	20
14″	14.18″	25.25″	22.00″	17.75″	3.38″	6.13″	.50″	1.63″	20
16″	16.19″	27.75″	24.25″	20.00″	3.50″	6.50″	.50″	1.75″	20
18″	18.20″	31.00″	27.00″	22.25″	4.00″	7.50″	.50″	2.00″	20
20″	20.25″	33.75″	29.50″	24.50″	4.25″	8.25″	.50″	2.13″	20
24″	24.25″	41.00″	35.50″	29.50″	5.50″	10.50″	.50″	2.63″	20

Lap-Joint Class 1500

Lap joint flange dimensions class 1500 in inches (ASME B16.5)

FLANGENPS	InsideDiameter	OutsideDiameter	Bolt Circle (BC)	Raised Face (R)	Raised Face (RF)	H	Raised Face Thickness (T)	T1	Flat Face Thickness (T2)	Bolt Hole (B)	No. of Bolt Holes
1/2″	0.88″	4.75″	3.25″	1.38″	.250″	1.50″	1.50″	0.88″	1.25″	0.88″	4
3/4″	1.09″	5.13″	3.50″	1.69″	.250″	1.75″	1.63″	1.00″	1.38″	0.88″	4
1″	1.36″	5.88″	4.00″	2.00″	.250″	2.06″	1.88″	1.13″	1.63″	1.00″	4
1-1/4″	1.70″	6.25″	4.38″	2.50″	.250″	2.50″	1.88″	1.13″	1.63″	1.00″	4
1-1/2″	1.95″	7.00″	4.88″	2.88″	.250″	2.75″	2.00″	1.25″	1.75″	1.13″	4
2″	2.44″	8.50″	6.50″	3.63″	.250″	4.13″	2.50″	1.50″	2.25″	1.00″	8
2-1/2″	2.94″	9.63″	7.50″	4.13″	.250″	4.88″	2.75″	1.63″	2.50″	1.13″	8
3″ **	3.57″	10.50″	8.00″	5.00″	.250″	5.25″	3.13″	1.88″	2.88″	1.25″	8
4″ **	4.57″	12.25″	9.50″	6.19″	.250″	6.38″	3.81″	2.13″	3.56″	1.38″	8
5″ **	5.66″	14.75″	11.50″	7.31″	.250″	7.75″	4.38″	2.88″	4.13″	1.63″	8
6″ **	6.72″	15.50″	12.50″	8.50″	.250″	9.00″	4.94″	3.25″	4.69″	1.50″	12
8″ **	8.72″	19.00″	15.50″	10.63″	.250″	11.50″	5.88″	3.63″	5.63″	1.75″	12
10″ **	10.88″	23.00″	19.00″	12.75″	.250″	14.50″	6.50″	4.25″	6.25″	2.00″	12
12″ **	12.88″	26.50″	22.50″	15.00″	.250″	17.75″	7.38″	4.88″	7.13″	2.13″	16

Lap-Joint Class 2500

Lap joint flange dimensions class 2500 in inches (ASME B16.5)

FLANGENPS	InsideDiameter	OutsideDiameter	Bolt Circle (BC)	H	T1	T2	RA	Bolt Hole (B)	No. of Bolt Holes
1/2″	0.90″	5.25″	3.50″	1.69″	1.19″	1.56″	.12″	0.88″	4
3/4″	1.11″	5.50″	3.75″	2.00″	1.25″	1.69″	.12″	0.88″	4
1″	1.38″	6.25″	4.25″	2.25″	1.38″	1.88″	.12″	1.00″	4
1-1/4″	1.72″	7.25″	5.13″	2.88″	1.50″	2.06″	.19″	1.13″	4
1-1/2″	1.97″	8.00″	5.75″	3.13″	1.75″	2.38″	.25″	1.25″	4
2″	2.46″	9.25″	6.75″	3.75″	2.00″	2.75″	.31″	1.13″	8
2-1/2″	2.97″	10.50″	7.75″	4.50″	2.25″	3.13″	.31″	1.25″	8
3″	3.60″	12.00″	9.00″	5.25″	2.63″	3.63″	.38″	1.38″	8
4″	4.60″	14.00″	10.75″	6.50″	3.00″	4.25″	.44″	1.63″	8
5″	5.69″	16.50″	12.75″	8.00″	3.63″	5.13″	.44″	1.88″	8
6″	6.75″	19.00″	14.50″	9.25″	4.25″	6.00″	.50″	2.13″	8
8″	8.75″	21.75″	17.25″	12.00″	5.00″	7.00″	.50″	2.13″	12
10″	10.92″	26.50″	21.25″	14.75″	6.50″	9.00″	.50″	2.63″	12
12″	12.92″	30.00″	24.38″	17.38″	7.25″	10.00″	.50″	2.88″	12

Lap-Joint Flanges Sizes in Millimeters

Lap-Joint Class 150

Lap joint flange dimensions class 150 in millimeters (ASME B16.5)

Sizeinch	Dmm	Xmm	tmm	B3mm	T3mm	R°
1/2	89	30.2	11.2	22.9	15.7	3.0
3/4	99	38.1	12.7	28.2	15.7	3.0
1	108	49.3	14.2	35.1	17.5	3.0
1¼	117	58.7	15.7	43.7	20.6	4.8
1½	127	65.0	17.5	50.0	22.4	6.4
2	152	77.7	19.1	62.5	25.4	7.9
2½	178	90.4	22.4	75.4	28.4	7.9
3	191	108.0	23.9	91.4	30.2	9.7
3½	216	122.2	23.9	104.1	31.8	9.7
4	229	134.9	23.9	116.8	33.3	11.2
5	254	163.6	23.9	144.5	36.6	11.2
6	279	192.0	25.4	171.5	39.6	12.7
8	343	246.1	28.4	223.3	44.5	12.7
10	406	304.8	30.2	277.4	49.3	12.7
12	483	365.3	31.8	328.2	55.6	12.7
14	533	400.1	35.1	360.2	79.2	12.7
16	597	457.2	36.6	411.2	87.4	12.7
18	635	505.0	39.6	462.3	96.8	12.7
20	699	558.8	42.9	514.4	103.1	12.7
24	813	663.4	47.8	616.0	111.3	12.7

Size (inch)	Bolt Circle Dia. (mm)	Holes #	Holes Dia. (mm)	Bolt Dia. (inch)	Length FF Flange	Length RF Flange	Length RTJ Flange
1/2	60.5	4	15.7	1/2	50.8	57.2	-
3/4	69.9	4	15.7	1/2	50.8	63.5	-
1	79.2	4	15.7	1/2	57.2	63.5	76.2
1¼	88.9	4	15.7	1/2	57.2	69.9	82.6
1½	98.6	4	15.7	1/2	63.5	69.9	82.6
2	120.7	4	19.1	5/8	69.9	82.6	95.3
2½	139.7	4	19.1	5/8	76.2	88.9	101.6
3	152.4	4	19.1	5/8	76.2	88.9	101.6
3½	177.8	8	19.1	5/8	76.2	88.9	101.6
4	190.5	8	19.1	5/8	76.2	88.9	101.6
5	215.9	8	22.4	3/4	82.6	95.3	108.0
6	241.3	8	22.4	3/4	82.6	101.6	114.3
8	298.5	8	22.4	3/4	88.9	108.0	120.7
10	362.0	12	25.4	7/8	101.6	114.3	127.0
12	431.8	12	25.4	7/8	101.6	120.7	133.4
14	476.3	12	28.4	1	114.3	133.4	146.1
16	539.8	16	28.4	1	114.3	133.4	146.1
18	577.9	16	31.8	11/8	127.0	146.1	158.8
20	635.0	20	31.8	11/8	139.7	158.8	171.5
24	749.3	20	35.1	1¼	152.4	171.5	184.2

Lap-Joint Class 300

Lap joint flange dimensions class 300 in millimeters (ASME B16.5)

Sizeinch	Dmm	Xmm	tmm	B3mm	T3mm	R°
1/2	95	38.1	14.2	22.9	22.4	3.0
3/4	117	47.8	15.7	28.2	25.4	3.0
1	124	53.8	17.5	35.1	26.9	3.0
1¼	133	63.5	19.1	43.7	26.9	4.8
1½	155	69.9	20.6	50.0	30.2	6.4
2	165	84.1	22.4	62.5	33.3	7.9
2½	191	100.1	25.4	75.4	38.1	7.9
3	210	117.3	28.4	91.4	42.9	9.7
3½	229	133.4	30.2	104.1	44.5	9.7
4	254	146.1	31.8	116.8	47.8	11.2
5	279	177.8	35.1	144.5	50.8	11.2
6	318	206.2	36.6	171.5	52.3	12.7
8	381	260.4	41.1	222.3	62.0	12.7
10	445	320.5	47.8	277.4	66.5	12.7
12	521	374.7	50.8	328.2	101.6	12.7
14	584	425.5	63.8	360.2	111.3	12.7
16	648	482.6	57.2	411.2	120.7	12.7
18	711	533.4	60.5	462.3	130.0	12.7
20	775	587.2	63.5	514.4	139.7	12.7
24	914	701.5	69.9	616.0	152.4	12.7

Size (inch)	Bolt Circle Dia. (mm)	Holes #	Holes Dia. (mm)	Bolt Dia. (inch)	Length FF Flange	Length RF Flange	Length RTJ Flange
1/2	66.5	4	15.7	1/2	57.2	63.5	76.2
3/4	82.6	4	19.1	5/8	63.5	76.2	88.9
1	88.9	4	19.1	5/8	63.5	76.2	88.9
1¼	98.6	4	19.1	5/8	69.9	82.6	95.3
1½	114.3	4	22.4	3/4	76.2	88.9	101.6
2	127.0	8	19.1	5/8	76.2	88.9	101.6
2½	149.4	8	22.4	3/4	82.6	101.6	114.3
3	168.1	8	22.4	3/4	88.9	108.0	120.7
3½	184.2	8	22.4	3/4	95.3	108.0	127.0
4	200.2	8	22.4	3/4	95.3	114.3	127.0
5	235.0	8	22.4	3/4	108.0	120.7	133.4
6	269.7	12	22.4	3/4	108.0	120.7	139.7
8	330.2	12	25.4	7/8	120.7	139.7	152.4
10	387.4	16	28.4	1	139.7	158.8	171.5
12	450.9	16	31.8	11/8	146.1	171.5	184.2
14	514.4	20	31.8	11/8	158.8	177.8	190.5
16	571.5	20	35.1	1¼	165.1	190.5	203.2
18	628.7	24	35.1	1¼	171.5	196.9	209.6
20	685.8	24	35.1	1¼	184.2	203.2	222.3
24	812.8	24	41.1	1½	203.2	228.6	254.0

Lap-Joint Class 600

Lap joint flange dimensions class 600 in millimeters (ASME B16.5)

Sizeinch	Dmm	Xmm	tmm	B3mm	T3mm	R°
1/2	95	38.1	14.2	22.9	22.4	3.0
3/4	117	47.8	15.7	28.2	25.4	3.0
1	124	53.8	17.5	35.1	26.9	3.0
1¼	133	63.5	20.6	43.7	28.4	4.8
1½	155	69.9	22.4	50.0	31.8	6.4
2	165	84.1	25.4	62.5	36.6	7.9
2½	191	100.1	28.4	75.4	41.1	7.9
3	210	117.3	31.8	91.4	46.0	9.7
3½	229	133.4	35.1	104.1	49.3	9.7
4	273	152.4	38.1	116.8	53.8	11.2
5	330	189.0	44.5	144.5	60.5	11.2
6	356	222.3	47.8	171.5	66.5	12.7
8	419	273.1	55.6	222.3	76.2	12.7
10	508	342.9	63.5	277.4	111.3	12.7
12	559	400.1	66.5	328.2	117.3	12.7
14	603	431.8	69.9	360.2	127.0	12.7
16	686	495.3	76.2	411.2	139.7	12.7
18	743	546.1	82.6	462.3	152.4	12.7
20	813	609.6	88.9	514.4	165.1	12.7
24	940	717.6	101.6	616.0	184.2	12.7

Size (inch)	Bolt Circle Dia. (mm)	Holes #	Holes Dia. (mm)	Bolt Dia. (inch)	Length FF Flange	Length RF Flange	Length RTJ Flange
1/2	66.5	4	15.7	1/2	76.2	69.9	76.2
3/4	82.6	4	19.1	5/8	88.9	82.6	88.9
1	88.9	4	19.1	5/8	88.9	82.6	88.9
1¼	98.6	4	19.1	5/8	95.3	88.9	95.3
1½	114.3	4	22.4	3/4	108.0	101.6	108.0
2	127.0	8	19.1	5/8	108.0	101.6	108.0
2½	149.4	8	22.4	3/4	120.7	114.3	120.7
3	168.1	8	22.4	3/4	127.0	120.7	127.0
3½	184.2	8	25.4	7/8	139.7	133.4	139.7
4	215.9	8	25.4	7/8	146.1	139.7	146.1
5	266.7	8	28.4	1	165.1	158.8	165.1
6	292.1	12	28.4	1	171.5	165.1	171.5
8	349.3	12	31.8	11/8	190.5	184.2	196.9
10	431.8	16	35.1	1¼	215.9	209.6	215.9
12	489.0	20	35.1	1¼	222.3	215.9	222.3
14	527.1	20	38.1	13/8	235.0	228.6	235.0
16	603.3	20	41.1	1½	254.0	247.7	254.0
18	654.1	20	44.5	15/8	273.1	266.7	273.1
20	723.9	24	44.5	15/8	285.8	279.4	292.1
24	838.2	24	50.8	17/8	330.2	323.9	336.6

Lap-Joint Class 900

Lap joint flange dimensions class 900 in millimeters (ASME B16.5)

Sizeinch	Dmm	Xmm	tmm	B3mm	T3mm	R°
1/2	121	38.1	22.4	22.9	31.8	3.0
3/4	130	44.5	25.4	28.2	35.1	3.0
1	149	52.3	28.4	35.1	41.1	3.0
1¼	159	63.5	28.4	43.7	41.1	4.8
1½	178	69.9	31.8	50.0	44.5	6.4
2	216	104.6	38.1	62.5	57.2	7.9
2½	244	124.0	41.1	75.4	63.5	7.9
3	241	127.0	38.1	91.4	53.8	9.7
4	292	158.8	44.5	116.8	69.9	11.2
5	349	190.5	50.8	144.5	79.2	11.2
6	381	235.0	55.6	171.5	85.9	12.7
8	470	298.5	63.5	222.3	114.3	12.7
10	546	368.3	69.9	277.4	127.0	12.7
12	610	419.1	79.2	328.2	142.7	12.7
14	641	450.9	85.9	360.2	155.4	12.7
16	705	508.0	88.9	411.2	165.1	12.7
18	787	565.2	101.6	42.3	190.5	12.7
20	857	622.3	108.0	514.4	209.6	12.7
24	1041	749.3	139.7	616.0	266.7	12.7

Size (inch)	Bolt Circle Dia. (mm)	Holes #	Holes Dia. (mm)	Bolt Dia. (inch)	Length FF Flange	Length RF Flange	Length RTJ Flange
1/2	82.6	4	22.4	3/4	108.0	101.6	108.0
3/4	88.9	4	22.4	3/4	114.3	108.0	114.3
1	101.6	4	25.4	7/8	127.0	120.7	127.0
1¼	111.3	4	25.4	7/8	127.0	120.7	127.0
1½	124.0	4	28.4	1	139.7	133.4	139.7
2	165.1	8	25.4	7/8	146.1	139.7	146.1
2½	190.5	8	28.4	1	158.8	152.4	158.8
3	190.5	8	25.4	7/8	146.1	139.7	146.1
4	235.0	8	31.8	11/8	171.5	165.1	171.5
5	279.4	8	35.1	1¼	190.5	184.2	190.5
6	317.5	12	31.8	11/8	190.5	184.2	196.9
8	393.7	12	38.1	13/8	222.3	215.9	222.3
10	469.9	16	38.1	13/8	235.0	228.6	235.0
12	533.4	20	38.1	13/8	254.0	247.7	254.0
14	558.8	20	41.1	1½	273.1	266.7	292.1
16	616.0	20	44.5	15/8	285.8	279.4	298.5
18	685.8	20	50.8	17/8	323.9	317.5	333.6
20	749.3	20	53.8	2	349.3	342.9	362.0
24	901.7	20	66.5	1½	438.2	431.8	457.2

Lap Joint Flange Tolerance

ASME B16.5 sets forth tolerances for lap-joint flanges to ensure proper fit, functionality, and sealing within piping systems. While the standard provides detailed specifications for various flange dimensions across different sizes and pressure classes, here is a summary of general tolerance values for key dimensions of lap-joint flanges according to ASME B16.5. For precise values, especially for specific flange sizes and classes, direct reference to the ASME B16.5 standard is advised.

Diameter of Bolt Circle (P):

Tolerance: ±1.6 mm (±1/16 inch) for flanges through NPS 24.

Diameter of Bolt Holes (Q):

Tolerance: The diameter is typically oversized by +3 mm (1/8 inch) relative to the nominal bolt size to allow for alignment discrepancies during installation.

Flange Thickness (T):

Tolerance: This may vary, but a general guideline for flanges up to NPS 24 is ±3 mm (±1/8 inch). This tolerance ensures that the flange has adequate strength while avoiding unnecessary weight.

Hub Diameter at Base (X):

Tolerance: This dimension is critical for the fit of the lap-joint flange over the stub end. Tolerances can vary but are required for ensuring a proper fit that facilitates easy alignment and assembly.

Outside Diameter of Flange (O):

Tolerance: ±1.6 mm (±1/16 inch) for flanges up to NPS 24, ensuring that the flange will properly fit within the mating piping components and supports.

Inside Diameter of Flange (B):

Tolerance: For lap-joint flanges, the inside diameter at the back of the flange (where it mates with the stub end) should closely match the outside diameter of the stub end. The tolerance is typically -0/+3 mm (-0/+1/8 inch) for smaller sizes, to ensure a snug fit without hindering the assembly.

Facing Finish:

Tolerance: The surface finish for the flange face that mates with the gasket is specified in terms of Ra (Roughness Average), with the standard providing specific values based on the type of gasket material used. This ensures an adequate seal is achieved.

Drilling:

Tolerance: Bolt holes are to be evenly spaced around the bolt circle, and the tolerance for the number of holes must be precise to ensure alignment with the mating flange.

Engineers and designers must adhere to these tolerances during flange fabrication, selection, and installation to ensure the integrity of the flanged joint and the overall piping system. Accurate implementation of these tolerances facilitates proper alignment, sealing, and function of the piping system under various operating conditions.

Lap-Joint Flange Weights

Lap-Joint Flange Weight in Kgs.

The table shows the ASME B16.5 Lap Joint flange weights in Kgs. by Flange NPS and Class (carbon/alloy steel materials; for higher grades, consider adjusting weight using the delta-specific weight carbon/other grades)

NPS	Class 150	Class 300	Class 400	Class 600	Class 900	Class 1500	Class 2500
1/2	0.5	0.9	0.9	0.9	2.7	2.7	3.2
3/4	0.9	1.4	1.4	1.4	2.7	2.7	3.6
1	0.9	1.4	1.6	1.8	3.4	3.6	5.4
1¼	1.4	2.1	2	2.3	4.5	4.5	7.7
1½	1.4	2.9	2.9	3.2	6.3	6.3	10.8
2	2.3	3.2	3.6	4.1	9.5	11.3	16.7
2½	3.6	4.5	4	5.4	11.3	15.8	23.9
3	4.1	6.5	6.3	6.8	13	21.2
3½	4	7.7	9	9			36
4	5.9	10.8	11.3	16.2	22	33.8	54.9
5	6.8	12.6	13	28.4	36.5	63	91.8
6	8.6	17.6	18.9	35.1	47.3	76.5	141.3
8	13.5	26.1	28.8	50.4	85.5	128.7	211.9
10	19.4	40	49.5	87.8	124.7	218.3	403.7
12	28.8	63	68.4	108	166	337.1	567.9
14	47.3	85.5	94.5	130.5	186.8	400.5
16	63	105.3	126	180	219.6	562.5
18	72	137.3	155.3	211.1	301.5	663.8
20	87.8	168.8	189	271.8	390.6	798.8
22	110.3	195.8	204.8	301.5
24	123.8	247.5	276.8	389.7	746.6	1271

Lap-Joint Flange Weight in Lbs.

The table shows the ASME B16.5 Lap Joint flange weights in Lbs. by Flange NPS and Class (carbon/alloy steel materials; for higher grades, consider adjusting weight using the delta-specific weight carbon/other grades)

CLASS 150	Nominal Pipe Size	Lap Joint Weight in Lbs./unit
	½	1
	¾	2
	1	2
	1¼	3
	1½	3
	2	5
	2½	8
	3	9
	3½	11
	4	13
	5	15
	6	19
	8	30
	10	43
	12	64
	14	105
	16	140
	18	160
	20	195
	22	245
	24	275
CLASS 300	Nominal Pipe Size	Lap Joint Weight in Lbs./unit
	½	2
	¾	3
	1	3
	1¼	4.5
	1½	6.5
	2	7
	2½	10
	3	14.5
	3½	17
	4	24
	5	28
	6	39
	8	58
	10	91
	12	140
	14	190
	16	234
	18	305
	20	375
	22	435
	24	550
CLASS 400	Nominal Pipe Size	Lap Joint Weight in Lbs./unit
	½	2
	¾	3
	1	3.5
	1¼	4.5
	1½	6.5
	2	8
	2½	11
	3	14
	3½	20
	4	25
	5	29
	6	42
	8	64
	10	110
	12	152
	14	210
	16	280
	18	345
	20	420
	22	455
	24	615
CLASS 600	Nominal Pipe Size	Lap Joint Weight in Lbs./unit
	½	2
	¾	3
	1	4
	1¼	5
	1½	7
	2	9
	2½	12
	3	15
	3½	20
	4	36
	5	63
	6	78
	8	112
	10	195
	12	240
	14	290
	16	400
	18	469
	20	604
	22	670
	24	866
CLASS 900	Nominal Pipe Size	Lap Joint Weight in Lbs./unit
	½	6
	¾	6
	1	7.5
	1¼	10
	1½	14
	2	21
	2½	25
	3	29
	4	51
	5	81
	6	105
	8	190
	10	277
	12	371
	14	415
	16	488
	18	670
	20	868
	24	1659
CLASS 1500	Nominal Pipe Size	Lap Joint Weight in Lbs./unit
	½	6
	¾	6
	1	8
	1¼	10
	1½	14
	2	25
	2½	35
	3	47
	4	75
	5	140
	6	170
	8	286
	10	485
	12	749
	14	890
	16	1250
	18	1475
	20	1775
	24	2825
CLASS 2500	Nominal Pipe Size	Lap Joint Weight in Lbs./unit
	½	7
	¾	8
	1	12
	1¼	17
	1½	24
	2	37
	2½	53
	3	80
	4	122
	5	204
	6	314
	8	471
	10	897
	12	1262