ASME B16.5 lap joint flange: dimensions by class

Flange that rotates freely over a stub end welded to the pipe. Makes aligning the bolt holes easier and allows a carbon steel flange with the stub end in the noble alloy.

Technical review Oct 2026 · Source: ASME B16.5-2020

Lap joint in section. Works with a stub end (ASME B16.9) welded to the pipe; it has no contact with the fluid.

StandardASME B16.5-2020

Classes150, 300, 400, 600, 900, 1,500, 2,500

Range in class 150NPS ½ to 24

Unitsmm, kg; hole and bolt in inches

Dimensions by pressure class

Choose the class and click a row: the drawing changes to the scale and dimensions of that diameter.

Lap joint, class 150: dimensions in mm · raised face 1.6 mm · all types in class 150
NPS	DN	O	tf	X	Y	B	r	W	No. of holes	Hole Ø	Bolt Ø
½"	15	89	11.2	30	16	22.9	3	60.5	4	⅝"	½"
¾"	20	99	12.7	38	16	28.2	3	69.8	4	⅝"	½"
1"	25	108	14.2	49	18	35.1	3	79.2	4	⅝"	½"
1¼"	32	117	15.7	59	21	43.7	5	88.9	4	⅝"	½"
1½"	40	127	17.5	65	22	50.0	6	98.6	4	⅝"	½"
2"	50	152	19.0	78	25	62.5	8	120.6	4	¾"	⅝"
2½"	65	178	22.4	90	28	75.4	8	139.7	4	¾"	⅝"
3"	80	190	23.9	108	30	91.4	10	152.4	4	¾"	⅝"
3½"	90	216	23.9	122	32	104.1	10	177.8	8	¾"	⅝"
4"	100	229	23.9	135	33	116.8	11	190.5	8	¾"	⅝"
5"	125	254	23.9	164	37	144.5	11	215.9	8	⅞"	¾"
6"	150	279	25.4	192	40	171.4	13	241.3	8	⅞"	¾"
8"	200	343	28.4	246	44	222.2	13	298.4	8	⅞"	¾"
10"	250	406	30.2	305	49	277.4	13	362.0	12	1"	⅞"
12"	300	483	31.8	365	56	328.2	13	431.8	12	1"	⅞"
14"	350	533	35.1	400	79	360.2	13	476.2	12	1⅛"	1"
16"	400	597	36.6	457	87	411.2	13	539.8	16	1⅛"	1"
18"	450	635	39.6	505	97	462.3	13	577.8	16	1¼"	1⅛"
20"	500	698.5	42.9	559	103	514.4	13	635.0	20	1¼"	1⅛"
22"	550	749	46.0	610	108	565.2	13	692.2	20	1⅜"	1¼"
24"	600	813	47.8	663	111	616.0	13	749.3	20	1⅜"	1¼"

Lap joint, class 300: dimensions in mm · raised face 1.6 mm · all types in class 300
NPS	DN	O	tf	X	Y	B	r	W	No. of holes	Hole Ø	Bolt Ø
½"	15	95	14.2	38	22	22.9	3	66.5	4	⅝"	½"
¾"	20	117	15.7	48	25	28.2	3	82.6	4	¾"	⅝"
1"	25	124	17.5	54	27	35.1	3	88.9	4	¾"	⅝"
1¼"	32	133	19.0	64	27	43.7	5	98.6	4	¾"	⅝"
1½"	40	155	20.6	70	30	50.0	6	114.3	4	⅞"	¾"
2"	50	165	22.4	84	33	62.5	8	127.0	8	¾"	⅝"
2½"	65	190	25.4	100	38	75.4	8	149.4	8	⅞"	¾"
3"	80	210	28.4	117	43	91.4	10	168.1	8	⅞"	¾"
3½"	90	229	30.2	133	44	104.1	10	184.2	8	⅞"	¾"
4"	100	254	31.8	146	48	116.8	11	200.2	8	⅞"	¾"
5"	125	279	35.1	178	51	144.5	11	235.0	8	⅞"	¾"
6"	150	318	36.6	206	52	171.4	13	269.7	12	⅞"	¾"
8"	200	381	41.1	260	62	222.2	13	330.2	12	1"	⅞"
10"	250	444	47.8	321	95	277.4	13	387.4	16	1⅛"	1"
12"	300	521	50.8	375	102	328.2	13	450.8	16	1¼"	1⅛"
14"	350	584	53.8	425	111	360.2	13	514.4	20	1¼"	1⅛"
16"	400	648	57.2	483	121	411.2	13	571.5	20	1⅜"	1¼"
18"	450	711	60.5	533	130	462.3	13	628.6	24	1⅜"	1¼"
20"	500	775	63.5	587	140	514.4	13	685.8	24	1⅜"	1¼"
22"	550	838	66.5	641	145	565.2	13	743.0	24	1⅝"	1½"
24"	600	914	69.9	702	152	616.0	13	812.8	24	1⅝"	1½"

Up to NPS 3½, class 400 uses the same dimensions as class 600 (rows marked "= 600").

Lap joint, class 400: dimensions in mm · raised face 6.4 mm · all types in class 400
NPS	DN	O	tf	X	Y	B	r	W	No. of holes	Hole Ø	Bolt Ø
½" = 600	15	95	14.2	38	22	22.9	3	66.5	4	⅝"	½"
¾" = 600	20	117	15.7	48	25	28.2	3	82.6	4	¾"	⅝"
1" = 600	25	124	17.5	54	27	35.1	3	88.9	4	¾"	⅝"
1¼" = 600	32	133	20.6	64	28	43.7	5	98.6	4	¾"	⅝"
1½" = 600	40	155	22.4	70	32	50.0	6	114.3	4	⅞"	¾"
2" = 600	50	165	25.4	84	37	62.5	8	127.0	8	¾"	⅝"
2½" = 600	65	190	28.4	100	41	75.4	8	149.4	8	⅞"	¾"
3" = 600	80	210	31.8	117	46	91.4	10	168.1	8	⅞"	¾"
3½" = 600	90	229	35.1	133	49	104.1	10	184.2	8	1"	⅞"
4"	100	254	35.1	146	51	116.8	11	200.2	8	1"	⅞"
5"	125	279	38.1	178	54	144.5	11	235.0	8	1"	⅞"
6"	150	318	41.1	206	57	171.4	13	269.7	12	1"	⅞"
8"	200	381	47.8	260	68	222.2	13	330.2	12	1⅛"	1"
10"	250	444	53.8	321	102	277.4	13	387.4	16	1¼"	1⅛"
12"	300	521	57.2	375	108	328.2	13	450.8	16	1⅜"	1¼"
14"	350	584	60.5	425	117	360.2	13	514.4	20	1⅜"	1¼"
16"	400	648	63.5	483	127	411.2	13	571.5	20	1½"	1⅜"
18"	450	711	66.5	533	137	462.3	13	628.6	24	1½"	1⅜"
20"	500	775	69.8	587	146	514.4	13	685.8	24	1⅝"	1½"
22"	550	838	73.2	641	152	565.2	13	743.0	24	1¾"	1⅝"
24"	600	914	76.2	702	159	616.0	13	812.8	24	1⅞"	1¾"

Lap joint, class 600: dimensions in mm · raised face 6.4 mm · all types in class 600
NPS	DN	O	tf	X	Y	B	r	W	No. of holes	Hole Ø	Bolt Ø
½"	15	95	14.2	38	22	22.9	3	66.5	4	⅝"	½"
¾"	20	117	15.7	48	25	28.2	3	82.6	4	¾"	⅝"
1"	25	124	17.5	54	27	35.1	3	88.9	4	¾"	⅝"
1¼"	32	133	20.6	64	28	43.7	5	98.6	4	¾"	⅝"
1½"	40	155	22.4	70	32	50.0	6	114.3	4	⅞"	¾"
2"	50	165	25.4	84	37	62.5	8	127.0	8	¾"	⅝"
2½"	65	190	28.4	100	41	75.4	8	149.4	8	⅞"	¾"
3"	80	210	31.8	117	46	91.4	10	168.1	8	⅞"	¾"
3½"	90	229	35.1	133	49	104.1	10	184.2	8	1"	⅞"
4"	100	273	38.1	152	54	116.8	11	215.9	8	1"	⅞"
5"	125	330	44.4	189	60	144.5	11	266.7	8	1⅛"	1"
6"	150	356	47.8	222	67	171.4	13	292.1	12	1⅛"	1"
8"	200	419	55.6	273	76	222.2	13	349.2	12	1¼"	1⅛"
10"	250	508	63.5	343	111	277.4	13	431.8	16	1⅜"	1¼"
12"	300	559	66.5	400	117	328.2	13	489.0	20	1⅜"	1¼"
14"	350	603	69.8	432	127	360.2	13	527.0	20	1½"	1⅜"
16"	400	686	76.2	495	140	411.2	13	603.2	20	1⅝"	1½"
18"	450	743	82.6	546	152	462.3	13	654.0	20	1¾"	1⅝"
20"	500	813	88.9	610	165	514.4	13	723.9	24	1¾"	1⅝"
22"	550	870	95.2	663	175	565.2	13	777.7	24	1⅞"	1¾"
24"	600	940	101.6	718	184	616.0	13	838.2	24	2"	1⅞"

Up to NPS 2½, class 900 uses the same dimensions as class 1500 (rows marked "= 1500").

Lap joint, class 900: dimensions in mm · raised face 6.4 mm · all types in class 900
NPS	DN	O	tf	X	Y	B	r	W	No. of holes	Hole Ø	Bolt Ø
½" = 1500	15	121	22.4	38	32	22.9	3	82.6	4	⅞"	¾"
¾" = 1500	20	130	25.4	44	35	28.2	3	88.9	4	⅞"	¾"
1" = 1500	25	149	28.4	52	41	35.4	3	101.6	4	1"	⅞"
1¼" = 1500	32	159	28.4	64	41	43.7	5	111.1	4	1"	⅞"
1½" = 1500	40	178	31.8	70	44	50.0	6	124.0	4	1⅛"	1"
2" = 1500	50	216	38.1	105	57	62.5	8	165.1	8	1"	⅞"
2½" = 1500	65	244	41.1	124	64	75.4	8	190.5	8	1⅛"	1"
3"	80	241	38.1	127	54	91.4	10	190.5	8	1"	⅞"
4"	100	292	44.5	159	70	116.8	11	235.0	8	1¼"	1⅛"
5"	125	349	50.8	190	79	144.5	11	279.4	8	1⅜"	1¼"
6"	150	381	55.6	235	86	171.4	13	317.5	12	1¼"	1⅛"
8"	200	470	63.5	298	114	222.2	13	393.7	12	1½"	1⅜"
10"	250	546	69.8	368	127	277.4	13	469.9	16	1½"	1⅜"
12"	300	610	79.2	419	143	328.2	13	533.4	20	1½"	1⅜"
14"	350	641	85.9	451	155	360.2	13	558.8	20	1⅝"	1½"
16"	400	705	88.9	508	165	411.2	13	616.0	20	1¾"	1⅝"
18"	450	787	101.6	565	190	462.3	13	685.8	20	2"	1⅞"
20"	500	857	108.0	622	210	514.4	13	749.3	20	2⅛"	2"
24"	600	1041	139.7	749	267	616.0	13	901.7	20	2⅝"	2½"

Lap joint, class 1500: dimensions in mm · raised face 6.4 mm · all types in class 1500
NPS	DN	O	tf	X	Y	B	r	W	No. of holes	Hole Ø	Bolt Ø
½"	15	121	22.4	38	32	22.9	3	82.6	4	⅞"	¾"
¾"	20	130	25.4	44	35	28.2	3	88.9	4	⅞"	¾"
1"	25	149	28.4	52	41	35.4	3	101.6	4	1"	⅞"
1¼"	32	159	28.4	64	41	43.7	5	111.1	4	1"	⅞"
1½"	40	178	31.8	70	44	50.0	6	124.0	4	1⅛"	1"
2"	50	216	38.1	105	57	62.5	8	165.1	8	1"	⅞"
2½"	65	244	41.1	124	64	75.4	8	190.5	8	1⅛"	1"
3"	80	267	47.8	133	73	91.4	10	203.2	8	1¼"	1⅛"
4"	100	311	53.8	162	90	116.8	11	241.3	8	1⅜"	1¼"
5"	125	375	73.2	197	105	144.5	11	292.1	8	1⅝"	1½"
6"	150	394	82.6	229	119	171.4	13	317.5	12	1½"	1⅜"
8"	200	483	91.9	292	143	222.2	13	393.7	12	1¾"	1⅝"
10"	250	584	108.0	368	178	277.4	13	482.6	12	2"	1⅞"
12"	300	673	124.0	451	219	328.2	13	571.5	16	2⅛"	2"
14"	350	749	133.4	495	241	360.2	13	635.0	16	2⅜"	2¼"
16"	400	826	146.0	552	260	411.2	13	704.8	16	2⅝"	2½"
18"	450	914	162.1	597	276	462.3	13	774.7	16	2⅞"	2¾"
20"	500	984	177.8	641	292	514.4	13	831.8	16	3⅛"	3"
24"	600	1168	203.2	762	330	616.0	13	990.6	16	3⅝"	3½"

Lap joint, class 2500: dimensions in mm · raised face 6.4 mm · all types in class 2500
NPS	DN	O	tf	X	Y	B	r	W	No. of holes	Hole Ø	Bolt Ø
½"	15	133	30.2	43	40	22.9	3	88.9	4	⅞"	¾"
¾"	20	140	31.8	51	43	28.2	3	95.2	4	⅞"	¾"
1"	25	159	35.1	57	48	35.1	3	108.0	4	1"	⅞"
1¼"	32	184	38.1	73	52	43.7	5	130.0	4	1⅛"	1"
1½"	40	203	44.4	79	60	50.0	6	146.0	4	1¼"	1⅛"
2"	50	235	50.8	95	70	62.5	8	171.4	8	1⅛"	1"
2½"	65	267	57.2	114	79	75.4	8	196.8	8	1¼"	1⅛"
3"	80	305	66.5	133	92	91.4	10	228.6	8	1⅜"	1¼"
4"	100	356	76.2	165	108	116.8	11	273.0	8	1⅝"	1½"
5"	125	419	91.9	203	130	144.5	11	323.8	8	1⅞"	1¾"
6"	150	483	108.0	235	152	171.4	13	368.3	8	2⅛"	2"
8"	200	552	127.0	305	178	222.2	13	438.2	12	2⅛"	2"
10"	250	673	165.1	375	229	277.4	13	539.8	12	2⅝"	2½"
12"	300	762	184.2	441	254	328.2	13	619.3	12	2⅞"	2¾"

Scale drawing

Section drawing, proportional to the table dimensions (mm).

O = outside diameter · tf = thickness without raised face · X = hub diameter at base · Y = overall length without raised face · B = bore · r = bore radius · W = bolt circle. * Weight estimated from geometry in carbon steel.

Frequently asked questions

What is the asme b16.5 lap joint flange: dimensions by class used for?

Flange that rotates freely over a stub end welded to the pipe. Makes aligning the bolt holes easier and allows a carbon steel flange with the stub end in the noble alloy.

Do the dimensions include the raised face?

No. Since the 2017 edition, the thickness (tf) and length (Y) in ASME B16.5 are measured without the raised face. Add 1.6 mm for classes 150 and 300 and 6.4 mm from class 400 upward.

In which materials does Dustre supply it?

A105 and A350 LF2 carbon steel, F304L and F316L stainless, F51/F60 duplex, F53/F55 super duplex, F11, F22 and F91 Cr-Mo, nickel alloys and titanium, forged and machined with 3.1 certificate.

Lap joint in special alloysForged and machined at Dustre, in any class, with 3.1 certificate.

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