ASME/ANSI B16.5 Class 1500 LJ

The lap joint flange is practically identical to a slip-on flange except it has a radius at the intersection of the bore and flange face. 

This radius is necessary to have the flange accommodate a lap joint stub end. Normally, a lap joint flange and a lap joint stub end are mated together is an assembly system.

Nominal Pipe Size	Outside Diameter of Flange	Thickness of Lap Joint Min.	Diameter of Hub	Length Through Hub	Bore	Corner Radius of Bore of Lapped Flange	Diameter of Bolt Circle	Diameter of Bolt Holes	Number of Bolts	Approxi-mate Weight kgs
NPS	O	tf	X	Y	B	r	W	I	n
1/2	120	22.3	38	32	22.9	3	82.6	22.2	4	1.69
3/4	130	25.4	44	35	28.2	3	88.9	22.2	4	2.28
1	150	28.6	52	41	34.9	3	101.6	25.4	4	3.41
1 1/4	160	28.6	64	41	43.7	5	111.1	25.4	4	3.89
1 1/2	180	31.8	70	44	50.0	6	123.8	28.6	4	5.41
2	215	38.1	105	57	62.5	8	165.1	25.4	8	9.57
2 1/2	245	41.3	124	64	75.4	8	190.5	28.6	8	13.54
3	265	47.7	133	73	91.4	10	203.2	31.8	8	17.29
4	310	54.0	162	90	116.8	11	241.3	34.9	8	27.02
5	375	73.1	197	105	144.4	11	292.1	41.3	8	51.41
6	395	82.6	229	119	171.4	13	317.5	38.1	12	60.85
8	485	92.1	292	143	222.2	13	393.7	44.5	12	103.41
10	585	108.0	368	178	277.4	13	482.6	50.8	12	181.39
12	675	123.9	451	219	328.2	13	571.5	54.0	16	286.48
14	750	133.4	495	241	360.2	13	635.0	60.3	16	384.80
16	825	146.1	552	260	411.2	13	704.8	66.7	16	492.31
18	915	162.0	597	276	462.3	13	774.7	73.0	16	638.30
20	985	177.8	641	292	514.4	13	831.8	79.4	16	766.56
24	1170	203.2	762	330	616.0	13	990.6	92.1	16	1227.85