PLUMBING WORKS



SPECIFICATIONS FOR PROVIDING PLUMBING SERVICES OF GAS SUPPLY SYSTEM IN BUILDINGS

21.0 Introduction

21.0.1 This section covers the safe use of gas for fuel or lighting purposes in buildings.

21.0.2 The use of gas for fuel and lighting purposes in buildings has begun in some parts of the country and with the advent of new petroleum complexes, community gas supply is bound to become one of the important services like electricity and water supply in buildings.

21.0.3 The use of liquefied petroleum gas supplied in containers and cylinders is also becoming increasingly popular.  On release of pressure, by opening the valve, they readily convert into the gaseous phase.  In this state they present a hazard comparable to any inflammable natural or manufactured gas, except that being heavier than air, low level, ventilation is necessary to avoid inflammable concentration of gas.

21.0.4 Minimum sets of safety regulations are, therefore, laid down to safeguard the gas piping installation and the mode of operation in the interest of public safety.

21.0.5 The information regarding the use of liquefied petroleum gas has been largely based on the following Indian Standards:

IS: 6044(Part 1)-1971 Code of practice for liquefied petroleum gas storage installations: Part 1 Commercial and industrial cylinder installations.

IS: 6044 (Part II)-1972 Code of practice for liquefied petroleum gas storage installations: Part II Industrial, commercial and domestic bulk storage installations.

Scope

21.1.1 This section covers the requirements regarding the safety of persons and property for all piping uses and for all types of gases used for fuel or lighting purposes in buildings.

21.1.2 This section does not cover safety rule for gas burning appliances. 

Pressure regulations

21.2.1 Where the pressure of gas supplied to domestic systems or other low pressure gas piping systems in buildings is in excess of 7kN/m2 a gas pressure regulator of sufficient size shall be installed in the service pipe of each such system to prevent pressure in excess of 7 kN/m2 from being introduced into such a building piping unless the building piping is of welded construction in which case the gas pressure regulator may be located up stream of gas meter in each consumer’s premises. In these cases, the gas pressure in piping down stream of gas pressure regulator shall not exceed 7 kN/m2.

21.2.2.  If located inside a building, the required regulator shall comply with the following:

a) If any of the diaphragms of the regulator ruptures, the gas shall be sent to an outlet vent pipe made of brass or plastic in order to ventilate or drain the gas out of the building.  The vent pipe will, however, lead to outer air about 1meter above the top most story of the building.  Means shall be employed to prevent water from entering this pipe and also to prevent the stoppage of it by insect or any other foreign bodies. 

b) If the gas pressure at the outlet of the regulator falls below 50% of the operating gas pressure or rises above twice the operating gas pressure, the gas input to the pressure reducer shall be cut off. 

c) In the event of mal functioning of this safety device, a supplementary shall connect the low pressure circuit to the outlet circuit (vent pipe) as soon as exit pressure reaches 7 kN/m2.

21.2.3 It shall also be insured by the supply authority that the calorific value and supply pressure of gas shall not exceed the values for the type of gas used,

Service shut-off valves

21.3.1 Service shut - off valves shall be installed on all new services including replacements in a readily accessible location.

21.3.2 Service shut-off valves shall be located upstream of the meter if there is no regulator or upstream of the regulator if there is one. 

21.3.3 All gas services, operating at pressure greater than 7 kN/m2 shall be equipped with an approved service shut-off valve located on the service pipe outside the building.

21.3.4 Underground shut-off valves shall be located in a covered durable curb box, man hole, vault or stand pipe which is designed to permit ready operation of the valve and the covers of which shall be clearly marked ‘Gas’.

Existing work

21.4.1 Nothing herein shall prohibit the continued use of existing system of the gas piping without further inspection or test, unless the Authority has reason to believe that defects which make the system dangerous to life or property exist.

Rules for turning gas on

21.5.1 No person, unless is the employ of the gas company or having permission from the gas company, shall turn on the gas at a service shut-off valve or at any valve that controls the supply of gas to more than one consumer.

21.5.2 Gas shall not be turned on at any meter valve without specific permission from the gas company or other authority if any of the following conditions exists:

  1. If the gas piping appliances or meter supply through the meter valve are known to leask or otherwise to be defective.
  2. If required inspection of the piping or appliance has not been made.
  3. If the gas company or other authority has requested that the gas be left turned off.
  4. If the meter valve is found shut off for some reason not known to the gas fitter.

21.5.3.  Gas shall not be turned on at any branch line valve if any of the conditions specified in 6.2 prevails.  Where a branch line valve is found closed, a gas fitter shall again turn the gas on at such valve only if proper precautions to prevent leakage are taken and no other unsafe conditions are created thereby. 

21.5.4. Gas shall not be turned on at either the meter valve or service line unless all gas keys or valves provided on all outlets in the piping system are closed or all outlets in the piping system are capped or plugged.

Rules for shutting off the gas

21.6.1 The gas fitter shall put the gas off to any appliance, pipe or piping system and leave the gas turned off, until the caused interrupting the supply has been removed any one of the following cases:

  1. If ordered to do so by the Authority.
  2. If leakage of gas is noted, which appears to be sufficient to cause fire, explosion or asphyxiation.
  3. If an installation of some gas appliance is found to be such as to cause a serious hazard to persons or property.
  4. If any condition exists which threatens interruption of gas supply which may cause burner outage or otherwise prove dangerous.

21.6.2 It shall be the duty of the installing agency when the gas supply is to be turned off to notify all affected consumers.

21.6.3 Before turning off the gas at the meter, for the purpose of installation, repair, replacement or maintenance of piping or appliances, all burner and pilot valves on the premises supplied with gas through the meter shall be turned off and the meter test hand observed for a sufficient length of time to ascertain that there is no gas passing through the meter.  Where there is more than one meter on the premises, precaution shall be exercised to assumed that the proper meter is turned off.

Installation of gas pipes

21.7.1 Installation, repair and replacement of gas piping or appliances shall be performed only by a qualified installing agency.

21.7.2 Piping

21.7.2.1 Piping shall be of wrought iron, steel, copper or cast iron when the gas pressure is less than 7 kN/m2; with higher gas pressure use of cast iron shall be prohibited.

21.7.2.1.1 Flexible metal pipes or heavy rubber pressure tubing shall be permitted only as direct connections to burners. 

21.7.2.2 Size of gas piping – Gas piping shall be of such size and so installed as to provide supply of gas sufficient to meet the maximum demand without undue loss of pressure between the meter or service regulator when a meter is not provided, and the appliance(s).

21.7.2.2.1 The size of gas piping depends upon the following factors:

a) Allowable loss in pressure from meter or service regulator, when a meter is not provided, to appliance;

b) Maximum consumption to be provided;

c) Length of piping and number of fittings; and

d) Specific gravity of gas.

21.7.2.2.2 No gas pipes smaller than 12 mm shall be used.

21.7.2.3 As for as possible, straight lengths of piping should be used.  Where there are bends in the pipe lines, these should have radius of at least 5 times the diameter of the pipe.

21.7.3 The gas piping shall be painted red so as to distinguish it from other piping and where piping is likely to be exposed to sun rays, it shall be painted silver grey.

21.7.4 Piping underground

21.7.4.1 Protection Of Piping – Piping shall be buried to a sufficient depth or covered in a manner so as to protect the piping from physical damage.

21.7.4.2 Protection Against Corrosion – Gas piping in contact with earth or other materials which may corrode the piping shall be protected against corrosion either by adopting cathode protection system where soil corrosion is heavy or by applying corrosion resisting paint like epoxy paint.  Piping shall not be laid in contact with cinders.

21.7.4.3 Underground gas piping shall be avoided as far as possible below grade through the foundation or basement walls of building, underground gas piping when installed below grade through foundation or basement wall of a building shall be either encased in a sleeve or otherwise protected against corrosion.

21.7.5 The building shall not be weakened by the installation of any gas piping.

21.7.6 Gas piping in building shall be supported with pipe hooks, metal pipe straps, bonds or hangers suitable for the size of piping and of adequate strength and quality and located at proper intervals so that the piping may not be moved accidentally from the installed position.

21.7.7 Pipe entrance to buildings – Where gas pipe enters a building through a wall or floor of masonry or concrete, any gas piping or other piping entering the walls or floors shall be suitably sealed against the entrance of water/moisture or gas.

21.7.7.1 Piping in floors – Piping in solid floors, such as concrete, shall be laid in channels in the floor suitably covered to permit access to the piping with a minimum damage to the building.

21.7.8 Gas pipe shall not be bent.  Fittings shall be used when making turns in gas pipe,

21.7.9 Gas piping shall not be supported by other piping.  Gas piping inside any building shall not be run in or through an air duct, chimney or gas vent, ventilating duct or elevator shaft.  Gas piping shall not be taken through inaccessible or concealed areas where their condition cannot be inspected and accumulation of gas due to undetected leakage may create a dangerous condition

21.7.10 A drip shall be provided in the gas distribution system, if the moisture contents in the gas is likely to reach saturation point at any stretch of pipe line in the system; a drip shall, however, be provided at any suitable point in the line of the pipe where condensate may collect and from where it can be easily removed.  This drip should be so installed as to constitute a trap wherein an accumulation of condensate will shut off the flow of gas before it will run back into the meter.

21.7.11 Prohibited devices - No device shall be placed inside the gas piping or fittings that will reduce the cross-sectional area or otherwise obstruct the free flow of gas.

21.7.12 Piping shall be electrically continuous throughout its length and properly earthed except in stretches where cathode protection system is used for protection against corrosion.  It shall not, however, be used to earth any electrical equipment.

21.7.12.1 The distance between gas piping and electrical wiring system shall be at least 60 mm and, where necessary, they shall be securely fixed to prevent con tact due to movement.  The gas piping should run below the electrical wiring.

21.7.13. The distance between the gas piping and steam piping, if running parallel, shall be at least 150 mm.  The gas piping should preferably run below the steam piping.

21.7.14 Piping installation shall be thoroughly gas tight.

21.7.15 Smoking shall not be permitted when working on piping which contains or has contaminated gas.

Inspection of services

  1. No person shall use or permit the use of a new system or an extension of an old system of gas piping in a building or structure before the same has been inspected and tested to ensure the tightness of the system and a certificate has been issued by the Authority.

21.8.1.1 Test of piping for tightness - Before any system of gas piping is finally put in service, it shall be carefully tested to ensure that it is gastight.  Where any part of the system is to be enclosed or concealed, this test should precede the work of closing in.  to test for tightness the piping may be filled with city gas, air or inert gas but not with any other gas or liquid.  In no case shall oxygen be used.  The piping shall stand a pressure of at least 20 kN/m2 measured with a manometer or slope gauge, for a period of not less than 10 minutes without showing any drop in pressure.

21.8.1.2 When the gas pressure exceeds 7 kN/m2, the piping shall withstand a pressure of 0.6 MN/m2 for 4 hours.  (This test is for piping designed for working pressure less than 0.4 MN/m2).

21.8.2 The Authority shall, within a reasonable time after being requested to do so, inspect and test a system of gas piping that is ready for such inspection and test, and if the work is found satisfactory and test requirements are complied with, it shall issue the certificate.

21.8.3 It shall be unlawful to supply gas in a building before the required certificate has been issued, except that the Authority may give temporary permission for a reasonable time to supply and use gas before such an installation has been fully completed and the certificate issued.

Leakage check

21.9.1 Before turning gas under pressure into any piping, all openings from which gas my escape shall be closed.

21.9.2 Checking for gas leakage - No matches, flame or other sources of ignition shall be employed to check for gas leakage from meters, piping or appliances. Checking for gas leakage with soap and water solution is recommended.

21.9.3 Use of lights - Artificial illumination used in connection with a search of gas leakage shall be restricted to electric hand flash lights (preferably of the safety type) or approved safety lamps.  In searching for leaks, electric switches should not be operated.  If electric lights are already turned on, they should not be turned off.

21.9.4 Checking for leakage with meter - Immediately after turning gas into the piping, the system shall be checked to ascertain that no gas is escaping.  This may be done by carefully watching the test dial of the meter to determine whether gas is passing through the meter.  In no case should a leakage test be made using a gas meter unless immediately prior to the test it has been determined that the meter is in operating condition

21.9.5 Checking of leakage without using a meter - This may be done by attaching to an appliance, orifice or a manometer or equivalent device and momentarily turning on the gas supply and deserving the gauging device for pressure drop with the gas supply shut-off. No discernible drop in pressure shall occur during a period of 3 minutes.

21.9.6 After piping has been checked, all gas piping shall be fully purged.  Piping shall not be purged into the combustion chamber of an appliance.  A suggested method for purging the gas piping to an appliance is to disconnect the pilot piping at the outlet of the pilot valve.

21.9.7 After the gas piping has been effectively purged, all appliances shall be purged and the pilots lighted

???????Use of liquefied petroleum gas (LPG)

21.10.1 The cylinders used for the storage and transportation of LPG shall conform to accepted standards [3(1)]* approved by the statutory authority. 

* In this section where reference is made to ‘accepted standards’ or ‘code of practice’ in relation to material specification, testing and other information, the appropriate document listed at the end of this section may be used as a guide to the interpretation of this term.

21.10.2 the handling, use, storage and transportation of liquefied petroleum gas in cylinders exceeding 500 ml water capacity shall be done in accordance with code of practice [3(2)]*.

21.10.3 LPG cylinder installation

21.10.3.0 The following recommendations apply to installation in commercial, industrial, educational and institutional premises.

21.10.3.1 General recommendations

21.10.3.1.1 Those responsible for the installation of cylinders, equipment and piping should understand the characteristics of LPG and be trained in good practice of handling, installing and maintaining installations.

21.10.3.1.2 The jointing compound used at different joints in the system shall conform to accepted standards [3(3)].  Hemp and similar materials shall not be used at the joint.  In any joint in which the thread provides a gastight seal, jointing compound shall be used only on the male thread.

21.10.3.1.3 Fire extinguishers of dry powder type or carbon dioxide type conforming to accepted standards [3(4)] shall be provided in places where LPG cylinder installations are situated and shall be located near such installations.  Two buckets filled with sand and two with water shall also be installed nearby.  The number, type and size of the fire extinguishers shall be as follows:

 

Number

Type

Capacity

a

For installations with LPG 40 to 200 kg

1

Dry powder

3.5 kg

b

For installations with LPG more than 200 and up to 320 kg

1

Dry powder or CO2

7.5 kg

4.5 kg

c

For installations with LPG more than 320 and up to 1000 kg

2

Dry powder or CO2

7.5 kg

4.5 kg

21.10.3.1.4 Liquefied petroleum gas shall not be transferred from the cylinders in which it is received to any other container.

21.10.3.2 Cylinder location

21.10.3.2.1 Stationary installations

a) Stationary installation not exceeding 40 kg of LPG may be installed indoors on any floor.  It is recommended to have a minimum floor area of 5 m2 for such an installation.

b) Stationary installations each not exceeding 40 kg of LPG may be installed indoors on any floor within the same workspace provided the minimum distance between two such installations is 3 m, the proportion of such installations to floor area is one installation per 5 m2 and the aggregate quantity of gas of all such installations does not exceed 200 kg. 

c) Stationary installation not exceeding 80 kg of LPG may be installed indoors on any floor provided the floor area for such an installation is not less than 12 m2.

d) Stationary installations each not exceeding 80 kg of LPG may be installed indoors on any floor and within the same workspace provided the minimum distance between two such installations is 3 m, the proportion of such installations to floor area is one installation per 12 m2 and the aggregate quantity of gas of all such installations does not exceed 200 kg.

e) Stationary installation not exceeding 320 kg of LPG may be installed indoors in an enclosed section of a building or a room reserved exclusively for this purpose and ventilated at low level directly to the outside air

f) Stationary installation above 320 kg [200 kg in case provision ‘e’ is not possible] but not exceeding 1000 kg shall be installed outdoors on ground level only.  A minimum distance of 3 m shall be maintained between an installation and any building, public place, roadways, and other surroundings.  The installation shall be protected from excessive weathering by sun, rain, etc and from tampering by unauthorized persons.  A lean to roof with expanded metal on angle-iron frame work on the sides is considered suitable for this purpose.  In any case, adequate ventilation at ground level to the outside air shall be provided.  The distance between two such installations shall be 3 m unless separated by a leak proof wall of fire resistant material upto at least one meter above the height of the manifold valve. 

g) Cylinders shall be installed upright with the valves upper most. 

h) Cylinders should not be placed below ground level and shall be at least one meter away from drains, culverts or entrances and openings leading to cellars and other depressions in which gas might accumulate. 

i) Cylinders containing more than 20 kg of gas shall not be located on floors above the ground level. 

j) Cylinders shall be located on a concrete or brick floor, preferably raised in case of outdoor installations.

k) Cylinders shall not be placed close to steam pipes or any other source of heat and shall be protected from the weather and direct sun’s heat.  Cylinders shall be placed at a distance of 3 m away from any other source of heat which is likely to rise the temperature of cylinders above the room temperature unless separated by metal sheet or masonry partition.

l) When cylinders are being connected or disconnected, there shall be no open flame or similar source of ignition in the vicinity; and smoking shall be prohibited.

21.10.3.2.2 Portable installations - When portability of cylinders is necessary, the following requirements shall be fulfilled:

a) The sum total capacity of the cylinders connected to each manifold shall not exceed 80 kg of LPG.  The total quantity of gas thus installed in a workspace shall not exceed 200 kg.

b) The regulator shall be connected directly tot he cylinder valve or to a manifold which shall be connected to the cylinder valves by means of rigid connections to give adequate support to the regulator.

c) At any time the total quantity of gas at portable installations shall be in proportion to the floor area as specified in 21.10.3.2.1 (a) to 21.10.3.2.1 (f).

21.10.3.3 Manifolds and pressure regulators

21.10.3.3.1 If pressure regulators, manifold headers, automatic change-over devices, etc, are connected to cylinders by flexible or semi flexible connectors, they shall be rigidly supported.  Copper tube pigtails and reinforced high pressure hoses are considered to be flexible or semi-flexible connectors for this purpose.

21.10.3.3.2 Pressure regulator fitted with a safety valve shall be either:

  1. installed in the open air, or
  2. vented to the open by means of a metal vent pipe connected to the safety valve outlet.

21.10.3.3.3 Care shall be taken that safety valve outlets do not become choked with dust or other foreign matter.

21.10.3.3.4 Suitable line shut-off valves shall be fitted for each appliance or burner when more than one appliance is connected to the gas supply.  Both ends of the connection to portable appliances shall be securely attached by means of clips.  Hose shall be of a type resistant to liquefied petroleum gas, 

21.10.3.3.5 The manifold headers which do not have to be taken in normal use should be braced or welded using a material conforming to accepted standards[(3)] and which shall have a melting point of at least 540º C. 

21.10.3.4 Instructions to consumers - A handbook containing all instructions with regard to the following aspects shall be supplied by the supplier to the consumers:

  1. operation of the whole system;
  2. how to recognize gas leaks;
  3. action to be taken in
  4. action to be taken in case of damage to, or failure of any part of the installation.

21.10.3.5 For detailed information regarding installation of LPG cylinders in commercial, industrial, educational and institutional premises, reference may be made to good practice 3(5).

21.10.4 LPG Bulk storage installations

21.10.4.0 The following recommendations apply to LPG bulk storage installations where storage tanks over 450 liters water capacity are used at industrial, commercial and domestic consumers’ premises.

The maximum capacity of an individual tank and group of tanks at industrial, commercial and domestic premises shall be as follows:

Premises

Maximum Water Capacity of an Individual Tank, litres

Maximum Water capacity of Group of Tanks, litres

Industrial

   Commercial

Domestic

130 000

 40 000

20 000

260 000

  80 000

  80 000

21.10.4.1 Location and spacing of storage tanks

21.10.4.1.1 Storage tanks shall be located outside the buildings and shall not be installed one above the other.

21.10.4.1.2 Each individual tank shall be located with respect to the nearest important building or group of buildings or line of adjoining property, which may be built in accordance with Table 1.  The distances given refer to the horizontal distance in plan between the nearest point of the storage tank and building/property line.

21.10.4.1.3 In heavily populated or congested areas the authority having jurisdiction may determine the need for other reasonable protective methods to be taken, such as provision of fire walls, etc.  If fire walls are to be provided, the authority may determine the extent to which the safety distances for above ground tanks may be reduced.

21.10.4.1.4 No LPG tank(s) shall be located within the bounded enclosures of any petroleum installation.  The minimum distance of separation between LPG storage tanks and any petroleum installation shall be as prescribed under the Petroleum Rules 1937 or as specified in Table 1 whichever is more.

21.10.4.1.5 The number of storage tanks in one storage installation shall not exceed six.  In case there are more than one storage installations, the safety distance between two installations shall be the same as the distance between the tanks and the property line in accordance with Table 1.

21.10.4.2. Bunding - Since LPG is heavier than air, storage tank shall not be enclosed within bund walls. The accumulation of flammable liquid under LPG tanks shall be prevented by suitably slopping the ground.

21.10.4.3 Protection

21.10.4.3.1 To prevent trespassing or tampering, the area which includes tanks, direct fired vapourisers, pumping equipment and loading and unloading facilities shall be enclosed by an industrial type fence at least 2 m high along the perimeter of the safety zone.  Any fence shall have at least two means of exit.  Gates shall open outwards and shall not be self locking.

Table 1 Minimum safety distances

(Clause 21.10.4.1.2 and 21.10.4.1.5)

Sl.No.

LPG Storage Water Capacity of Individual Tank

Distance from Building/

Property Line

Distance Between Tanks

 

(1)

 

(2) litres

Above Ground

Under Ground

Above Ground

Under Ground

(3) m

(4) m

(5) m

(6)  m

I

Up to 2 000

5

5

1

1.5

ii

Above 2000 and up to 10000

10

7.5

1

1.5

iii

Above 10000 and upto 20000

15

10

1.5

1.5

iv

Above 20000 and upto 40000

20

-

2

-

v

Above 40000 and upto 130000

20

-

2

-

Note 1 – If the aggregate water capacity of a multi-tank installation is 40 000 litres or greater, the above minimum safety distances shall apply to the aggregate storage capacity rather than the capacity per individual storage tank.

Note 2 – In view of lack of experience of underground tank installations in India, underground tanks larger than 20 000 litres water capacity shall not be permissible at present.

21.10.4.3.2 When damage to LPG systems from the LPG tank lorry is a possibility, precautions against such damage shall be taken.

21.10.4.3.3 underground tanks shall be protected from above ground loading by providing a suitable curb to prevent a possible accidental damage to the tank and its fittings by LPG tank lorry.

21.10.4.4 Grass and weed removal – Road ignitable material, such as weeds, long grass or any combustible material shall be removed from an area within 3 m from the shell of any LPG tank of up to 2 000 litres water capacity, and within 6 m from the shell of larger tanks.  If weed killers are used, chemicals which are a potential source of fire hazard shall not be selected for this purpose.

21.10.4.5 Warning signs - No smoking or naked flames shall be permitted within the safety zone of the installation. Prominent notices to this effect shall be posted at access point.

21.10.4.6 Fire protection - The possibility of a major fire outbreak, leading to direct flame impingement of the storage tank, shall be minimized by sound engineering in plant design and layout, good operating practice, and proper education and training of personnel on both routine operations and on action to be taken in an emergency.

21.10.4.6.1. Water supply - Provision shall be made for an adequate supply of water and fire protection in the storage area according to the local hoses and mobile equipment, fixed monitors or by fixed spray systems which may be automatic.  Control of water flow should be possible from outside any danger area.

21.10.4.6.2 Fire extinguishers - At least two dry chemical powder type fire extinguishers of 10 kg capacity each shall be installed at points of access to the storage installations.

21.10.4.7 For detailed information regarding LPG bulk storage installations reference may be made to code of practice.

Annexure 21-A.1

LIST OF STANDARDS

1) IS: 3196-1992 Specification for welded low carbon steel gas cylinder exceeding 5 litre water capacities for low pressure liquefiable gases (third revision).

IS: 7142-1975 Specification for welded low carbon steel gas cylinder for low pressure liquefiable gases not exceeding 5-litre water capacity.

2) IS: 8198 (Part V)-1984 Code of practice for steel cylinders for compressed gases: Part V Liquefied petroleum gases (LPG).

3) IS: 3465-1966 Specification for jointing compounds for use in liquefied petroleum gas appliances and installations.

4) IS: 2171-1985 Specification for portable fire extinguishers, dry powder type (second revision).

IS: 2878-1986 Specification for portable fire extinguishers, carbon-dioxide type (first revision).

5) IS: 6044(Part I)-1971 Code of practice for liquefied petroleum gas storage installations: Part I Commercial and industrial cylinder installations.

6) IS: 6044 (Part II)-1972 Code of practice for liquefied petroleum gas storage installations: Part II Industrial, commercial and domestic bulk storage installations.

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