Design calculation to proove pressure handling capability of 3 VALVE MANIFOLD ( DRAWING # )

Design calculation to prove pressure handling capability of HB Series Needle Valves (DRAWING # PNV-H-S-8-MF)The HB Series Needle Valve assembly consists of the following major parts (Refer detailed drawing No PNV-H-S-8-MF/4 )1. Gland Retainer

2. Gland Body

3. Spindle

4. Lock Nut5. Retainer Washer 6. Packing Support7. Gland Washer8. Packing - Teflon

Pressure withstand capacity required of manifold

= 10,000 psi

= 10,000 psi / 2.2 x 2.54 x 2.54

= 704 Kg/cm2 (1 Kgs = 2.2 lbs; 1 inch = 2.54 cm)The vee-tip of the spindle closes an orifice of diameter 4mm = 0.4cm = do

do2 = (0.4)2 = 0.1256 cm2

Area of orifice hole =Force on spindle required to withstood at 10000 Psi when the valve is in closed condition = pressure x area = 704 kg/cm2 x 0.1256 cm2 = 88.42 kg.

Pressure withstanding capability shall be checked at the following threaded joints:1. Spindle to gland retainer threading.2. Gland Retainer to gland Body threading.3. Gland body to main body threading.1) Pressure withstand capability calculation for spindle to gland retainer threading :

Thread type M8; Thread pitch = 1.25mm = 0.125cm = t1Thread length = 2.0mmNo of threads = threading length / pitch

= 20/1.25

= 16

Minimum root diameter of threading = 6.647mm = 0.6647cm = d1Tensile / shear strength for material of Spindle is SS316 is 84 ksi = 84000 psi =

84000 = 5918 kg/cm2 = T

2.2 x 2.54 x 2.54

(1 kg = 2.2 lbs; 1 inch = 2.54 cm)Shear withstand area of each thread = d1 x t1 = 3.14 x 0.6647 x 0.125 = 0.26 cm2Shear withstand area of 16 threads

= 0.26 x 16 = 4.16 cm2 = A1Shear withstand force capability threaded spindle

= T x A1 = 5918 x 4.16 = 24618 Kgs

Factor of safety = Shear withstand force capability = 24618 = 278.42 Shear withstand force required 88.42Thus the spindle of gland retainer threading is adequately rated for pressure capability required.

2) Pressure withstand capability calculation for Gland retainer to gland body threading :Thread type M16; Thread pitch = 1.5mm, = 0.15cm. = t2Threading length = 29mmNo threads = 29/1.5 = 19.33 = 19 threadsMinimum root diameter of threading = 14.376mm = 1.4376 cm = d2Tensile shear strength of SS316 material = T = 5918 kg/cm2Shear withstand area of each thread = d2 t2 = 3.14 x 1.4376 x 0.15 = 0.677 cm2Shear withstand area of 10 threads = 19 x 0.677 = 12.863 cm2.= A2Shear withstand force capability of above threaded joint

= T X A2 = 5918 x 12.863 = 76123 Kg

Factor of Safety = 76123 = 860

88.42

Thus, this threaded joint is also adequately rated for pressure capability required.

3) Pressure withstand capability calculation for gland body to main body threading :

Thread type M18; Thread pitch = 1.5mm = 0.15cm = t3Threading length = 7.5mmNo of threads = 7.5mm / 1.5mm = 5 threadsMinimum root diameter of threading = 16.376mm = 1.6376 cm = d3Tensile shear strength of SS316 Material = T = 5918 Kg/cm2Shear withstand area of each thread

= d3 t3 = 3.14 x 1.6376 x 0.15 = 0.77 cm2.

Shear withstand area of 5 threads

= 5 x 0.77 = 3.85 cm2. = A3Shear withstand force capability of above threaded joint

= T x A3 = 5918 X 3.85 = 22784 KgFactor of safety = 22785 / 88.42 = 257.67Thus, this threaded joint is also adequately rated for the pressure capability required.

Pressure withstanding capability shall also be checked at

4) Section A-A which is the weakest section area in the gland retainer. ( Refer Drawing No PNV-H-S-8-MF/2-1 )

5) Section B-B which is the weakest section area in the gland body ( Refer Drawing no PNV-H-S-8-MF/2- 2 )

4. Pressure withstand capability calculation for section A-A of gland retainer ( Drawing no PNV-H-S-8-MF/2-1)D0 = 14.376 mm = 1.4376 cm

Di = 8 mm = 0.8 cmTensile withstand area of this section

= D02 Di2 )

4

= 1.43762 0.82 )

4

= 0.64) 4

= 1.119 cm2 = A4 Tensile shear strength of SS316 Material = T = 5918 Kg/cm2Tensile withstand force capability of this section

= T x A4 = 5918 X 1.119 = 6622 KgFactor of safety = Force withstand capability available=6622 =74.89 Force withstand capability required

88.42Thus, this section is adequately rated for pressure capability required.

5. Pressure withstands capability calculation for section B-B of gland body (Refer. Drawing PNV-H-S-8-MF/2-2)Tensile withstand area of this section

D0 = 16.376 mm = 1.6376 cmDi = 10.1 mm = 1.01 cm= D02 Di2 )

4

= 1.63762 1.012 )

4

= 1.02) 4

= 1.3 cm2 = A5 Tensile shear strength of SS316 material = T = 5918 Kg/cm2Tensile withstand force capability of this section

= T x A5 = 5918 x 1.3 = 7693.40 KgFactor of Safety

= 7693.40 = 87.00 88.42Thus, this section is adequately rated for the pressure capability required.

Summary: The weakest possible points of Needle Valve assembly have been found to be adequately rated to withstand a pressure 10,000 psi.The Bar Stock Stainless steel body sections (Drawing # PNV-H-S-8-MF/1) are even more rated to withstand the pressure capable and hence not checked.