SWG PIPES

GUIDELINES FOR FACTORY INSPECTION OF SWG pipes (IS 651 - 2007)

1. Marking

Every pipe and fitting shall have legibly impressed upon it before firing the following

Name or trade mark of the manufacturer
Size ( internal dia)
Class of pipe

2. Sampling

a) Scale of sampling for Physical dimensions:

Sl.No	Lot Size	Sample	Sample Size	Cumulative sample size	General quality and Dimensions ( Sections A & B)
Sl.No	Lot Size	Sample	Sample Size	Cumulative sample size	ac	rc
1	Up to 150	First	20	20	1	4
		Second	20	40	4	5
2	151 to 280	First	32	32	2	5
		Second	32	64	6	7
3	500 to 1200	First	80	80	5	9
		Second	80	160	12	13
4	1201 to 3200	First	125	125	7	11
		Second	125	250	18	19
5	3201 to 10,000	First	200	200	11	16
		Second	200	400	16	27

b) Sampling for Chemical & Mechanical Tests (Water absorption, Acid resistance test, Alkali resistance test and Crushing Strength)

Lot Size	No of pipes to be tested
Up to 150	3
151 to1 200	5
1201 to 10, 000	8

c) Hydraulic test: The no of pipes or fittings to be tested for Hydraulic test shall be 5 % of the lot.

Physical Measurements

Internal Diameter

Sl. No	Internal Dia (mm)	Tolerance percent (%)
1	100- 350	±3
2	400-800	±2.5

Thickness of Barrel and socket

Sl. No	Internal Dia (mm)	Tolerance(mm)
1	100- 350	±3
2	Not exceeding 450	±2
3	500 & 600	±3
4	700 & 800	±5

Internal depth of socket
Excess shoulder measurement
Length of pipe( Tolerance -1.5 % & + 4 % mm )
Length of grooving of spigot
Grooving: The interior of the sockets and exterior of the spigots shall be grooved circumferentially, and such grooving on the spigot shall be for a length equal to one and half times the depth of sockets, and depth of grooves shall be between 1 mm to 2.5mm.

Dimensions of Barrels and Sockets:

Sl.No	Internal Diameter	Class	Mean thickness of Barrel & socket( Min)	Internal depth of socket (min)	Excess shoulder measure ment(Min)	Length of grooving of spigot (Min)
1	100	Sp1	12	50	10	75
		Sp2	14	55	11	82.5
		Sp3	18	60	14	90
2	150	Sp1	15	57	11	85.5
		Sp2	16	60	12	90
		Sp3	20	62	12	93
3	200	Sp1	16	63	12	94.5
		Sp2	18	65	13	97.5
		Sp3	22	68	15	102
4	230	Sp1	19	63	12	94.5
		Sp2	21	65	14	97.5
		Sp3	24	68	16	102
5	250	Sp1	20	70	16	105
		Sp2	22	66	17	99
		Sp3	26	69	18	103.5
6	300	Sp1	25	70	16	105
		Sp2	24	72	18	108
		Sp3	28	74	19	111
7	350	Sp1	30	75	16	112.5
		Sp2	32	76	20	114
		Sp3	34	76	20	114
8	400	Sp1	35	75	16	112.5
		Sp2	36	77	20	115.5
		Sp3	38	77	20	115.5
9	450	Sp1	37	76	16	114
		Sp2	40	78	20	117
		Sp3	45	79	20	118.5
10	500	Sp1	40	80	19	120
		Sp2	45	85	20	127.5
		Sp3	50	90	20	135
11	600	Sp1	43	90	19	135
		Sp2	50	95	22	142.5
		Sp3	55	100	22	150
12	700	Sp1	50	95	20	142.5
		Sp2	55	100	23	150
		Sp3	60	110	23	165
13	800	Sp1	55	100	24	150
		Sp2	65	110	26	165
		Sp3	75	120	27	180

Tests at Factory:
Hydraulic test :

When subjected to the hydraulic test, straight pipes shall withstand an internal hydraulic test pressure of 0.15 MPa on the barrels and without showing signs of injury or leakage.

The pressure shall be applied on pipes shall be maintained for at least 5 s. Care shall be taken to ensure that all air is expelled before the test commenced.

Pressure to be applied for pipes – 0.15 MPa
Duration of test – 5sec

Water Absorption test:

Size of specimen - 50 Sq cm - to 130 Sq cm.
Sample required to be dried at Temperature not less than 150° C in oven and bring at room temperature and Weigh it W1.
Immersion of sample in water for an hour
Take the immersed sample and keep it for room temperature and weigh it W2.

Increase in mass, percent = W3 / W1 * 100

Where, W1 – Mass of dry specimen, (in grams)

W2 - Mass of specimen after immersion (in grams)

W3= W2 – W1

The percentage increase in mass of each test piece by absorption of water shall not exceed the following values.

Sl.No	Thickness of pipes or fitting (mm)	Increase in mass percent
1	Up to and including 20	6
2	Over 20 and up to 25	7
3	Over 25 and up to 32	8
4	Over 32 and up to 38	9
5	Over 38	10

.Acid Resistance test:

Size of specimen – 5 cm square, not more than 200 g in mass
Liquid needed for immersion 4.9% sulphuric acid and balance distilled water.
Sample required to be dried at temperature not less than 150° C in oven and bring the same at room temperature. Weigh the same as W1
Immerse in above prepared solution (in step ‘b’) for 48 hrs after the process of step ‘c’.
Remove the sample and clean the samples with hot water so that the washed water falls in above prepared solution ( in step ‘b’) .
Filter the solution processed in step ‘e’ and add 5ml of concentrated sulphuric acid.
Heat the above solution until evaporates and only residue left in crucible.

Loss in mass, percent = W4/ W1 * 100

Where, W1 – Initial weight of sample, (in grams)

W2 – weight of crucible (in grams)

W3 – weight of crucible + residue (in grams)

W4 - W3 – W2

The loss in mass shall not exceed 2.5%.

4. Alkali Resistance test:

Size of specimen: 75 sq cm to 130 sq cm.
Liquid for test solution of Magnesium sulphate and distilled water
Solution should be boiled and sample should be submerged up to 2 hrs in boiling solution.
Remove the sample and keep it in oven for heating not less than 110° C then bring the sample to room temperature.’
Step ‘c ’ and step ‘d ’ should be repeated 5 cycles

After the completion of 5 cycles there shall be no evidence or pitting softening spalling or cracking.

5. Crushing strength test:

When tested along the full length of the pipe barrel from shoulder to spigot, the crushing strength of each class of pipes or pipe sections shall be not less than the values given below:

Sl.No	Internal diameter (mm)	Class
Sl.No	Internal diameter (mm)	SP1 (Kn/m)	SP2 (Kn/m)	SP3 (Kn/m)
1	Up to 150	16	18	21
2	200 to 300	16	21	24
3	350 to 450	16	26	32
4	500 to 800	16	32	60

6. Load Calculation for SP1 class pipe measuring 0.6 m length:

RAM Diameter = 7.5 cm ; Area of Ram = (3.14/4)*(7.5*7.5) = 44.18 sqcm

As per crushing strength table, load to be applied for SP1 class pipe = 16 kN/m

= 16 x 1000/100 = 160 N/cm

Hence for 60 cm pipe load to be applied = 160x60 = 9600 KN

Now 1 Kg = 9.8 N

Converting Load applied into Kg = 9600/9.8 = 979.59 kg

Hence Crushing load to be applied (in Kg/sqcm) = Load/ Area of RAM = 979.59/ 44.18

= 22.17 kg/sq cm.

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