The AMERICAN Lok-Ring joint is a restrained joint that utilizes the sealing features of the time-proven AMERICAN Fastite joint. It is an essentially boltless, flexible restrained connection that provides an easily assembled positive restraint against endwise separation due to thrust resulting from internal pressure or external forces. Only a minimal amount of time is required to complete the Lok-Ring assembly, or disassembly if necessary.
The patented1 AMERICAN Lok-Ring joint is designed for working pressures up to 250 psi for sizes 60" through 64". If higher pressure ratings are needed, contact AMERICAN. The Lok-Ring joint can be used with any lesser pressure class of ductile iron pipe, with the maximum operating pressure rating of the joint limited in such cases to that of the pipe. An alloy steel welded-on retainer ring and a split lok-ring, assembled behind the retainer ring, provide the means of restraint. The split lok-ring is held “snug” and constricted against the pipe OD for assembly of the AMERICAN Fastite portion of the joint. After the plain end of the pipe is assembled into the Lok-Ring bell, the lok-ring is released, permitting it to expand. The lok-ring is thus securely positioned behind the welded-on retainer ring and in the socket locking groove on the ID of the Lok-Ring bell. This locks the joint.
The lok-ring, welded retainer ring and all parts of the closure-spreader mechanism are all constructed of corrosion-resistant, high-strength, low-alloy (HSLA) steel. This is the same type of steel specified for bolting material per ANSI/AWWA C111/A21.11, and it has been used successfully in several AMERICAN restrained joint constructions for approximately 50 years. The weld is aluminum bronze, and both the weld and ring are cathodic to – and thus protected by – the greater mass of the ductile iron pipe. Welding is performed using welders qualified to produce high-quality, dependable welds.
The AMERICAN Lok-Ring joint utilizes standard Fastite gaskets and lubricant, and, like the Fastite joint, the Lok-Ring joint is designed to permit deflection in order to facilitate installation and accommodate settlement. It is noted that rotation of the lok-ring under great loads helps to distribute the forces substantially around and between the bell and spigot members.
AMERICAN Lok-Ring Pipe is ductile iron, grade 60-42-10, manufactured and tested in accordance with AWWA C151. It is normally furnished standard asphaltic-coated outside and cement-lined inside in accordance with AWWA C104. When specified, other special linings can be furnished. Fittings are available in both bell-bell and bell-plain end configurations for installation versatility and economy.
1.) U.S. Patents 4,428,604 and 4,524,505.
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 | ||||
|---|---|---|---|---|---|---|---|
Type 1 | Type 2 | Type 3 | Type 4 | Type 5 | |||
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’.
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 psi1 | Nominal Thickness (in.) | Laying Conditions | ||||
|---|---|---|---|---|---|---|---|
Type 1 | Type 2 | Type 3 | Type 4 | Type 5 | |||
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.
