APPENDIX A FORMULAE AND SAMPLE CALCULATIONS

1 APPENDIX AFORMULAE AND SAMPLE CALCULATIONSPipe Installation (Fused)The fused polyethylene (PE) pipe can be pulled by a cable attached to a pulling head fastened to thepipe. This prevents damage to the PE pipe. The length of the fused pipe which can be pulled will varydepending upon field conditions and ease of access to the area. In general, the maximum pulling lengthfor small diameter pipe, 12 inch and smaller, is normally limited to 1000 feet, and for larger pipe, about500 feet. Longer lengths have been pulled, however, all conditions must be determined. The variouspulling forces and lengths information is desirable for design and estimating purposes. The maximumforce that can be applied to a pipe on level ground can be determined by the following formula:Pt = (smax) A(1)WherePt =maximum pulling force (lb)smax=maximum allowable tensile stress, 1000 psiA=cross sectional area of pipe, in2 Note:HDPE primary properties are specified by cell classification per ASTM D3350.

2 Tensile strength is normally cell class 4 which is 3000 to 3500 psi. Theallowable tensile stress of 1000 psi provides a design factor of approximately 3to compensate for installation following formula can be used to determine the pulling length:L = Pt faWhere L = pulling length (feet)f = friction coefficient ( ) SAMPLE CALCULATIONS :1. 1000 feet of 12 inch, SDR 26 is being pulled over smooth ground with a 5o slope. What is the pulling force?t = inches d = - = C = BdA = Cxt = p x x = in2Pt = 1000 x = 18,870 weight per foot:V = A x 12 = (12) = in3 Weight = ( ) = lbs/ftThe maximum straight line of pipe that should be pulled (assuming f = ) is:L = 18,870 ( )L = 4838 feetNote:The maximum radius of curvature should be limited to maximum axial strainproperties of the pipe, as discussed Bending (Fused)Bending induced during the insertion step in transporting pipe lengths from assembly sites to jobsites, or permanent bends to accommodate line or grade changes should be limited to radii equivalentto a longitudinal strain recommended by the pipe manufacturer.

3 The minimum allowable radius ofcurvature for any size and weight of pipe can be closely approximated from the following equation:Rc = Do (3) 2 eaWhere:Rc = radius of curvature, = outside diameter of inserted pipe, in. ea = allowable axial strain = 1%This equates to:Rc = Do = Do = 50 Do 2( ) :The allowable axial strain has a design factor of at least 3, however, the manufacturer should beconsulted regarding their recommended long term allowable Trench (Fused)The minimum length of the trench from which the fused polyethylene pipe is inserted into theexisting pipeline to be rehabilitated can be calculated as a function of the pipe invert depth from groundsurface, H and the permissible bend radius using the equation:L $ [H (2R-H)1/2(4)R = 50 or greater times PE pipe Do orR = 50 Do (5)See figure A1 for pit trench configurationEXAMPLE.]

4 PE pipe Do = inchesHeight of cover, H = 12 feetR = 50 (24) = 1200 inches (100 feet)L $ [12 (2 x 100 - 12)]1/2 = [12 (188)]1/2L # [2256]1/2 = Use 48 feetPipe Installation (Gasketed)The gasketed pipe joint segments can be pushed and/or pulled into the existing pipeline from aninsertion pit. The pipe joints should be inserted with spigot end first and the bell end trailing. Thepush/pull bearing plate should be applied against the flat surface of the bell step, to avoid damaging thebell, especially on plastic pipe (HDPE). The maximum pushing and/or pulling length is determined bythe longitudinal compressive strength of the pipe and this varies with type of material and its access pit should be approximately 5 to 10 feet longer than the standard 20 foot pipe segmentlengths. The width of the pit should be 2 to 4 feet wider than the diameter of the existing pipe.

5 In general, the maximum push/pull lengths for 18-inch and larger slipliner pipe is normally limitedto 1000 feet in a dry sewer and about twice that in an active flowing existing pipeline condition, , alignment and grade changes, structural and corrosionconditions, etc., must be determined prior to the installation. The maximum push/pull force to beapplied can be determined by the following formula. Pc = smax A(6)Pc = maximum push/pull force, = maximum allowable compressive stress psiA = cross sectional area* of pipe, in2* located at minimal cross sectionFrom Roark, axial compressive stress, psismax = Et (7) r(SF)E = use initial tensile or compressive modulust = minimum wall thickness, = mean radius, inSF = Safety Factor usually - (for materials)The following formula can be used to determine the push/pull = Pc fa (SF) Where L = estimated push/pull length (feet) f = friction coefficient (= in dry & = in wet)a= pipe weight (lbs/ft) SF = (for installation) SAMPLE the estimated force needed and length of 36-inch inner profile wall HDPE pipe(RSC 160) that can be pushed/pulled through a dewatered (dry)

6 42-inch RCP pipeline. Pipeweighs 42 lbs/ft. Zbar = = in I = I = t3/12 t = = Et r(SF)E = 113,000 psit = in (effective)r = ( - ) / 2 = = = (113,000) = 1333 psi ( )Force needed:Pc = Fmax Asmax = 1333 psi, A = B dt = B ( ) = = 1333 ( ) = 234,248 lbsL = 234,248 = 5578 Ft. (42) ( ) the estimated force needed and length of 36-inch diameter exterior profile wallHDPE pipe (RSC 160) that can be pushed/pulled through a dry 42-inch RCP. Pipe weighs42 RoarkAxial Compressive Stress = E t r (SF)E = 113,000 psi (initial tensile modulus)t = inches (wall thickness raceway)SF = 2, r = (36 + ) / 2 = inchesAxial Comp.

7 Stress = (113,000) = 336 psi (2)From Formula (6)Pc = 336 ( x x ) = profile wall does not make contact along its entire surface. Adjusted friction values are: f = (dry) and f = (wet). When using HDPE Pipe, the normal friction factors should be used, , f = and Formula (7)L = 13,817 = 658 feet (42) (2) calculation :Determine the estimated force needed and length of 36-inch RPM pipe that can bepushed/pulled through a dry 42-inch RCP. The axial compressive stress of the RPM pipe is14,000 psi. The pipe stiffness is 36 psi having a wall thickness of weighs 71 = inches, t = , Effective t = inchesFrom Formula (6)P = 14,000 ( x x )P = 740,222 lbs (w/o SF) andP = 185,055 lbs (w/4 to 1 - SF) Force usedFrom Formula (7)L = 185,055 = 2606 feet - length (71) (2)Hydrostatic LoadsWhen there is a possibility of groundwater level above the pipe, the level and its duration should beestimated, and pipe of sufficient wall thickness to withstand the pressure, without collapsing, should beused.

8 It should be noted that an appropriate safety factor of 2 should be used. The following basicequation should be used to determine needed wall thickness:P = 24 Ea I (8) (1- 2)d3(FS)P = pressure due to head of water, psiEa = apparent (time-corrected) modulus, psid = mean diameter, inches = Poisson ratioFS = Safety Factor (normally )Note:Formula (8) is taken from Timoshenko/Von MisesIn order to determine needed wall thickness:P = 2Ea (t)3 (1- 2) (d)3 (FS)(9)t = [P(1- 2) d3(FS)]1/3 [2 Ea]1/3(10)Formula (8-10) applies primarily to solid wall pipe, such as, High Density Polyethylene,Polyvinyl Chloride, Steel Pipe, Ductile Iron Pipe and CIPP (See note below).Note: CIPP is Cured-in-Place-Pipe (Epoxy resin)The following mathematical modification of Formula (9) may be used when utilizing the dimensionalratio (DR).

9 P = 2 Ea (1- 2) (DR-1)3 (FS) (11)In order to determine needed dimensional ratio:(DR-1)3 = 2E (1- 2) P (FS)DR = [ 2Ea ]1/3 + 1 (12) (1- 2) P (FS)Note: Apply an appropriate Safety Factor (normally )The following product material Poisson ratios should be used:MaterialPoisson RatioHDPE following product material initial flexural modulus (Ei) values should be modified for apparent longterm values (Ea):MaterialEi (Initial-psi)HDPE 113,000 PVC 400,000 RPM x 106 CIPP 300,000 Steel 30 x 106*DIP 24 x 106** Initial and long term assumed to be the slipliner pipe is subjected to a constant on-going loading, the following apparent modulus valuesshould be (long term - psi)*HDPE 24,000 PVC 113,000 RPM x 106 CIPP 150,000 Steel 30 x 106**DIP 24 x 106** *Long term values set at 50 years, determine by long term stress regression testing.

10 **The wall thickness should be increased for corrosion allowance, usually inch or :The manufacturer's long term Modulus values must be obtained through acceptable long Hydrostatic LoadsWhen the annulus between the slipliner pipe and the existing pipe to be lined exceeds one inch, it isrecommended that this space be grouted. This grout, when set, provides restraining support for theslipliner pipe. Research has determined that this support enhances the buckling resistance by at least sixtimes that without the grout. The hydrostatic buckling can be determined by using the followingadjusted formula:P = 2 K Ea t3 (1- 2) d3 (FS) (13)t = [ P (1- 2) d3 (FS)]1/3(14) [2 KEa] 1/3P = 2K Ea (15) (1- 2) (DR-1)3 (FS)DR-1 = [ 2 K Ea ] 1/3 [ (1- 2) P(FS)] 1/3(16)K = grout support factorK = 7 (CIPP)K= 6 all other pipesGrout the annular space between the OD of the installed liner pipe and the ID of the existing pipe witha cement or chemical based grout.