Scope of Work: Provide and install buried steel pipe of the sizes and in the locations shown on the drawings and as specified herein.
Prior to the start of manufacturing, the following shall be submitted to, and approved by the engineer:
Gasketed Joints: The standard joint for working pressures up to 250 psi (72-inch maximum diameter) shall be rubber gasketed unless otherwise noted on the plans. Gasketed joints shall conform to AWWA C200 Standard and be either the Carnegie or rolled groove type. Rolled groove gasketed joints shall consist of a flared bell end formed and sized by the use of a segmental expander or by forcing the pipe end over a plug die. The spigot end groove, designed to retain the rubber gasket, shall be formed and sized by rolling on male-female dies to match the bell.
The gasket shall have sufficient volume to approximately fill the area of the groove and shall conform to AWWA C200.
The joint shall be suitable for the pressures of the class of pipe on which it is furnished, and shall operate satisfactorily with a deflection, the tangent of which is not to exceed 0.75 inch/D where D is the outside diameter of the pipe in inches, or with a uniform pull-out of ¾ inch.
Rubber gasketed joints may be furnished only by a manufacturer who has furnished pipe with joints of similar design for comparable working pressure, pipe diameter, pipe length, and wall thickness.
Shop applied coating shall be continuous to the end of the pipe on the bell end and shall be held back on the spigot end sufficiently to allow full engagement of the joint. Shop applied lining shall be continuous to the end of the pipe on the spigot end and shall be held back on the bell end to the point of maximum engagement or further as recommended by the manufacturer. For gasketed joints, the exposed surfaces of the bell and spigot shall be painted with one shop coat of a holding primer.
Welded Lap Joints: Field welded lap joints shall be used where restrained joints are indicated on the plans and for all pipe sizes over 72-inch diameter or working pressures greater than 250 psi.
The bell shall provide for a nominal lap such that the minimum engagement, with 1-inch allowable pull, is at least 1 inch or three times the thickness of the bell, whichever is greater. Shop applied lining and coating shall be held back sufficiently to allow for welding of the joint, except that lining shall be continuous to the end of the spigot for pipe diameters 24 inches and smaller.
Couplings: Couplings where indicated on the plans shall be bolted sleeve type conforming to AWWA C 219 such as Baker or Smith Blair or approved equal, or Split Sleeve Style conforming to AWWA C 227 such as Victaulic or approved equal. Couplings shall be restrained as required by the specifications and as shown in AWWA M11.
Couplings for buried service shall have all metal parts coated with epoxy paint conforming to AWWA C210 or powder coated conforming to AWWA C213.
Pipe for use with couplings shall have ends prepared to meet the requirements of the coupling manufacturer. Buried pipe with couplings must have the pipe ends held round for most couplings to perform properly. Consult with the coupling manufacturer for pipe end tolerances and out-of-roundness limitations for both installing the couplings and for in service performance of the couplings.
Pipe shall be designed for internal pressure using the hoop stress formula:
t=pd/2s
Where:
t = nominal pipe wall thickness for the specified internal design pressure, in. p = internal design pressure, psi d = outside diameter of steel pipe cylinder (not including coatings), in. s = allowable design stress, psi. Allowable design stress shall be 50% of steel yield strength for working pressure and 75% of steel yield strength for surge or test pressure, psi
The predicted earth load on the pipe shall be calculated using the prism of earth method as described in AWWA M11 which is shown below:
Wc = wHe(Dc/12)
Wc = Prism Load = dead load on the conduit. Lb/lin ft. of pipe w = unit weight of fill – lbs per cu ft Hc = height of fill above top of pipe ft Dc = outside diameter of coated pipe. In
Predicted deflection shall be calculated using the Modified Iowa formula from AWWA M11 and as shown below:
Δx = Dl[(KWr3)/(EI + 0.061E’r3)]
Δx = predicted horizontal deflection of pipe, in Dl = 1.0 (deflection lag factor) K = 0.1 (bedding constant) W = load per unit of pipe length = [Wc/12 + WlDc/144] r = mean radius of pipe E = modulus of elasticity, 30,000,000 psi for steel (Es) and 4,000,000 psi for cement-mortar (Iy & Ic) I = transverse moment of inertia per unit length of individual pipe wall components (for steel cylinder (IS), for cement-mortar lining (IL), and for cement-mortar coating (IC) = t3/12, in.3 E’ = Modulus of soil reaction = 1000 psi*
*Note to specifier - E’ varies with type of soil, compaction, and depth of cover. 1,000 psi represents a coarse-grained soil compacted to 90% standard proctor density at 2 to 5 ft of cover. For more values see AWWA Manual M11-5th Edition Table 5-3. It is almost always more economical to enhance the stiffness of the soil with compaction or utilize better soils if deflection controls the design of the wall thickness. E’ can be increased from 1,000 psi to 1,600 psi by increasing compaction from 90% to 95% standard proctor density. Values of E’ of 3,000 psi to 10,000 psi can be achieved by using soil cement (CLSM).
Tex EnochInduron Protective Coatings
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