Mechanical Joint Coupled Joint Pipe

The Mechanical Joint (MJ) Coupled Joint offers a method of providing joint restraint with a standard mechanical joint socket of a pipe, fitting, valve or other product. It is available in sizes 4" through 12" with a pressure rating of 350 psi and deflection capability up to 2 1⁄2°, and in 14" through 54" with a pressure rating of 250 psi intended for installation in essentially straight alignment. Check AMERICAN if larger sizes or greater deflections are desired. The MJ Coupled Joint is commonly used as a method of joint restraint for mechanical joint all-bell fittings and especially to restrain MJ valves.

The joint material consists of a standard mechanical joint gasket and a standard ductile iron joint gland. The restraint gland1 is ductile iron and is factory assembled on the pipe behind a welded-on 1⁄2" square alloy steel retaining ring. All MJ Coupled Joint restraining hardware is recommended to be Type 304 stainless steel. Tee-head bolts are special-length bolts.

Note: It is sometimes possible to provide for field-cutting and positive, even “drop-in” field-adaptable restraint in restrained piping areas by using modified MJ Coupled joints where the weld ring and restraint gland are intentionally moved farther away from the joint, and the standard short studs of the joint are replaced by longer threaded rods in the field. Threaded rods, of course, can also be cut to suit in the field. Similar effect can also be accomplished utilizing standard fabricated, stuffing-box couplings and similarly modified “Coupling Gland Ends.” Contact AMERICAN for additional information on this.

1.) The restraint gland for 30"-54" sizes is a substantially rectangular cross-section ductile iron gland.

Maximum Depths of Cover

for Minimum Pressure Classes of Ductile Iron Pipe ANSI/AWWA C151/A21.51

This table tabulates the maximum depth of cover for the five types of laying conditions, along with corresponding nominal wall thickness and maximum rated working pressure, all for minimum pressure classes of ductile iron pipe. Taken from the table that follows, it is offered as a convenience for quickly checking the capabilities of minimum pressure classes of ductile iron pipe under a given set of conditions.

For the majority of internal pressure and external loading conditions, minimum pressure classes are more than adequate and possess substantial safety factors.

Size (in.)	Pressure Class	Thickness (in.)	Laying Conditions Maximum Depth of Cover in Feet1
Size (in.)	Pressure Class	Thickness (in.)	Type 1	Type 2	Type 3	Type 4	Type 5
4	350	0.25	53	61	69	85	1004
6	350	0.25	26	31	37	47	65
8	350	0.25	16	20	25	34	50
10	350	0.26	112	15	19	28	45
12	350	0.28	102	15	19	28	44
14	250	0.28	see3	112	15	23	36
16	250	0.3	see3	112	15	24	34
18	250	0.31	see3	102	14	22	31
20	250	0.33	see3	10	14	22	30
24	200	0.33	see3	82	12	17	25
30	150	0.34	see3	-	9	14	22
36	150	0.38	see3	-	9	14	21
42	150	0.41	see3	-	9	13	20
48	150	0.46	see3	-	9	13	20
54	150	0.51	see3	-	9	13	20
60	150	0.54	see3	52	9	13	20
64	150	0.56	see3	52	9	13	20

1.) An allowance for single H-20 truck with 1.5 impact factor is included for all sizes and all depths of cover.

2.) Minimum allowable depth of cover is 3’. For depths less than 3’, consult AMERICAN.

3.) Laying condition Type 1 is limited to 12" and smaller pipe. For 14" and larger pipe, laying condition Type 1 should not be used.

4.) Calculated maximum depth of cover exceeds 100’.

Maximum Depths of Cover

for All Pressure Classes of Ductile Iron Pipe ANSI/AWWA C151/A21.51

This table lists maximum depths of cover for the five types of laying conditions for all standard pressure classes; also tabulated are the corresponding nominal wall thickness and maximum rated working pressure. (Note: Although not listed in the following table, ductile iron pipe for working pressures higher than 350 psi is available. Consult AMERICAN regarding specific conditions involved.)

Size (in.)	Pressure Class psi5	Nominal Thickness (in.)	Laying Conditions Maximum Depth of Cover in Feet6
Size (in.)	Pressure Class psi5	Nominal Thickness (in.)	Type 1	Type 2	Type 3	Type 4	Type 5
4	350	0.25	53	61	69	85	1008
6	350	0.25	23	31	37	47	65
8	350	0.25	16	20	25	34	50
10	350	0.26	117	15	19	28	45
12	350	0.28	107	15	19	28	44
14	250	0.28	see9	117	15	23	36
14	300	0.3	see9	13	17	26	42
14	350	0.31	see9	14	19	27	44
16	250	0.31	see9	117	15	24	34
16	300	0.32	see9	13	17	26	39
16	350	0.34	see9	15	20	28	44
18	250	0.31	see9	107	14	22	31
18	300	0.34	see9	13	17	26	36
18	350	0.36	see9	15	19	28	41
20	250	0.33	see9	10	14	22	30
20	300	0.36	see9	13	17	26	35
20	350	0.38	see9	15	19	28	38
24	200	0.33	see9	87	12	17	25
24	250	0.37	see9	11	15	20	29
24	300	0.4	see9	13	17	24	32
24	350	0.43	see9	15	19	28	37
30	150	0.34	see9	-	9	14	22
30	200	0.38	see9	88	12	16	24
30	250	0.42	see9	11	15	19	27
30	300	0.45	see9	12	16	21	29
30	350	0.49	see9	15	19	25	33
36	150	0.38	see9	-	9	14	21
36	200	0.42	see9	88	12	15	23
36	250	0.47	see9	10	14	18	25
36	300	0.51	see9	12	16	20	28
36	350	0.56	see9	15	19	24	32
42	150	0.41	see9	-	9	13	20
42	200	0.47	see9	8	12	15	22
42	250	0.52	see9	10	14	17	25
42	300	0.57	see9	12	16	20	27
42	350	0.63	see9	15	19	23	32
48	150	0.46	see9	-	9	13	20
48	200	0.52	see9	8	11	15	22
48	250	0.58	see9	10	13	17	24
48	300	0.64	see9	12	15	19	27
48	350	0.7	see9	15	18	22	30
54	150	0.51	see9	-	9	13	20
54	200	0.58	see9	8	11	14	22
54	250	0.65	see9	10	13	16	24
54	300	0.72	see9	13	15	19	27
54	350	0.79	see9	15	18	22	30
60	150	0.54	see9	57	9	13	20
60	200	0.61	see9	8	11	14	22
60	250	0.68	see9	10	13	16	24
60	300	0.76	see9	13	15	19	26
60	350	0.83	see9	15	18	22	30
64	150	0.56	see9	27	9	13	20
64	200	0.64	see9	8	11	14	21
64	250	0.72	see9	10	13	16	24
64	300	0.8	see9	12	15	19	26
64	350	0.87	see9	15	17	21	29

5.) These pipes are adequate for the rated working pressure indicated for each nominal size plus a surge allowance of 100 psi. Calculations are based on a 2.0 safety factor times the sum of working pressure and 100 psi surge allowance. Ductile iron pipe for working pressures higher than 350 psi is available.

6.) An allowance for a single H-20 truck with 1.5 impact factor is included for all sizes and all depths of cover.

7.) Minimum allowable depth of cover is 3’. For depths less than 3’, consult AMERICAN.

8.) Calculated maximum depth of cover exceeds 100’.

9.) Laying condition Type 1 is limited to 12" and smaller pipe. For 14" and larger pipe, laying condition Type 1 should not be used.

For other conditions not covered in these tables see AWWA C150 or consult AMERICAN for design of pipe thickness. Special thickness classes may be appropriate in such cases.

Maximum Depths of Cover

for Minimum Pressure Classes of Ductile Iron Pipe ANSI/AWWA C151/A21.51

Maximum Depths of Cover

for All Pressure Classes of Ductile Iron Pipe ANSI/AWWA C151/A21.51

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