The Static and Mobile Pressure Vessels 
(Unfired) Rules, 1981

21.    General

1. vessels meant for storage of compressed gas shall be installed entirely above-ground that is to say no part of the vessel shall be buried below the ground level.
   

2. Vessels and first stage regulating equipment shall be located in the open.
   

3. Vessels shall not be installed one above the other.
   

4. Vessels within a group shall be located that their longitudinal axes are parallel to each other.
   

5. No vessel shall be located within the bonded area of petroleum or other flammable liquid storages.
   

6. Sufficient space shall be provided between two vessels to permit firefighting liquid storages.
   

7. Two or more vessels installed in batteries shall be so installed that the top surface of the vessels are on the same plane.
   

8. Vessels installed with their dished ends facing each other shall have screen walls in between them.

22.    Location of pressure vessels

Each vessel shall be located with respect to the nearest building or group of buildings or line of adjoining property which may be built on and with respect to other vessels in accordance with the distance specified in the tables below :-

Table 1

Minimum safety distances for flammable corrosive and toxic gases.

Table 2

Minimum safety distance for non-toxic gases.

Note – 1.     If the aggregate water capacity of a multivessel installation is 40,000 litres or more the above minimum safety distance shall apply to the aggregate storage capacity.

Note – 2.      The number of storage vessels in one installation shall not exceed six. In case there are more than one installation the safety distance between two installations shall be the same as the distance between the vessels and the property line in accordance with table 1.

Note – 3.       The distance specified above are required to be measured from the nearest point on the periphery of the vessel.

Note – 4.       The distance specified above may be reduced by the chief controller in cases where he is of the opinion that additional safety measures have been provided.

23. Foundations for pressure vessels

1. General: The materials, principles methods and details of design and construction of foundations and supports of vessels shall comply with approved specifications standards or codes.

2. Ground conditions: A thorough knowledge of the ground condition shall be obtained by the person installing the vessel with particular reference to establishing an allowable beating pressure total and differential settlements expected risk of floatation and possible deterioration of original conditions.

3. Materials :

1.  The choice of materials for construction shall be determined by the ground conditions loading and detailed design constructions.

2. The materials may be of –

(a)    brick – work masonry ;

(b)    re-inforced concrete ; or

(c)    steel plate, steel pipe or structural steel. 

4. Loading : The greatest combined effect of static and imposed loadings shall be used for design as under :

(a)              Static loading : weight of vessel and its contents ;

(b)             Test loading if tested by water;

(c)              Wind loading;

(d)             Operational loading such as vibration or thermal (natural and operational). 

5.  Settlement: Any particular differential settlement shall be limited to prevent excessive stress in the connected pipe work and vessel shell.
   

6.   Vessel supports :

(i)                   the design of supports for vessels shall follow the standard or code to which the vessel is constructed ;

(ii)                 the spacing of vessel support shall be decided after close consideration of vessel – shell stressing and transmission of  the loadings to the ground;

(iii)                the design of supports for vessels shall provided flexibility to allow for movement of the vessel as a result of pressure and thermal expansion;

(iv)               the vessel shall be securely anchored or weighed or provided with adequate per height to avoid flotation due to flood waters ;

(v)                 in case of structural steel supports such supports excluding vessel saddles or supporting feet 45 cm or less height shall be encased in fire – resisting materials of adequate thickness. 

24. Fencing

1. The area where vessels pumping equipment loading and unloading facilities and direct fired vaporisers are provided shall be enclosed by an industrial type fence at least 2 metres high along the perimeter of the safety zone. 

2. Every fence shall have at least two means of exit and the gates of such exits shall open outwards and shall not be self-locking.

25. Cleanliness

An area of three metres around the vessel shall be kept free from readily ignitable materials such as weeds and long dry grass. 

26. Earthing

1. All vessels used for storage of flammable liquefiable gases shall be electrically connected with the earth in an efficient manner.

2. Pipelines conveying flammable liquids shall be adequately prepared for electrical continuity and connected with the earth in an efficient manner.

27. No. Smoking

A permanent notice with letters at least 5 cms in height prohibiting smoking and naked light shall be fixed to the fence surrounding the area where flammable or oxidising gases are stored and the notice shall be visible from outside.

28. Fire protection

All vessels used for the storage of flammable compressed gases shall be protected against the hazards as under : 

(i)                   Provision shall be made for an adequate supply of water and fire protection in the storage area according to the local fire service regulations. the application of water may be by hydrants, 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;

(ii)                 hydrants where provided shall be readily accessible at all times and so spaced as to provided for the protection of all vessels;

(iii)                Sufficient length of fire hose shall be provided and be readily available. the outlet of each hose line shall be equipped with combination jet and fog nozzle. the hoses should be maintained well and periodically inspected;

(iv)               mobile equipment fixed monitors or fixed spray systems shall be designed to discharge water at a rate sufficient to maintain an adequate film of water over the surface of the vessel and supports under fire conditions;

(v)                 consideration shall be given to the provision of mobile or fixed water spray systems giving suitable and effective protection for vehicle loading and unloading areas;

(vi)               at least two dry chemical power type fire extinguishers of 9 kg. capacity each shall be installed at each point of access to the installations.

29. Loading and unloading facilities.

    (1) Pumps :

(i)                   pumps may be centrifugal or positive displacement pumps ;

(ii)                design materials and construction of pumps shall be designed for the maximum outlet pressure to which they will be subjected to in operation;

(iii)                positive displacement pumps shall have a by –pass valve or other suitable protection against over pressure. 

(2)      Compressors :

(i)                   the design material and construction of compressors shall be suitable for the type of gas which they are to handle and they shall be designed for the maximum outlet pressure to which they will be subjected to in operation;

(ii)                 compressors other than multi – stage compressors shall take suction from the vapour space of the vessels beging filled. 

(3)      Transfer systems :

(i)                   transfer systems shall be so designed that the risk of a gas of a higher vapour pressure being transferred to equipment designed for gas of a lower vapour pressure is minimized;

(ii)                 there shall be positive means of rapidly shutting off flow located at a safe distance from the vessel which is being filled or emptied ;

(iii)                automatic alarm device to indicate the approach to maximum permissible height of automatic shut – off valves shall be used to prevent overfilling. 

(4)      Hoses :

(i)                   The hoses for liquid transfer shall be designed to withstand not less than four times the maximum operating pressure they will carry in service;

(ii)                 The hoses shall be mechanically and electrically continuous.

30. Transfer Of Operations

1. before transfer of gas:

(i)                   every vehicle shall be carefully examined at the installation to ensure that it complies in all respects with the requirements of these rules and shall be completely emptied it is passed for filling ;

(ii)                a visual check shall be made of the surroundings for unusual or dangerous situations before any filling or discharging procedure is commenced ;

(iii)                warning notice as necessary shall be displayed ;

(iv)               the receiving vessel shall be checked to ensure that it has hoses shall be checked to ensure that it is in safe working condition and that only valves and other fittings required in the transfer operations or any other operations proceeding simultaneously are open.

2. During transfer the receiving vessel shall be checked to ensure that it is not being filled above its safe filling capacity or beyond its design pressure.
   

3. On completion of transfer before the vehicle is allowed to leave the licensed premises it shall be weighed over a weigh – bridge to ascertain the quantity of the compressed gas filled therein if the vehicle is filled with a liquefiable gas.
   

4. When filling the vessels on vehicles with compressed gas the following procedure shall be complied with in addition to the other requirements namely :-

1. the place where the vehicle is parked shall be properly levelled ;
   

2.  the vehicle shall be prevented from accidental movement during the transfer operation. The parking brack of the engine shall remain stopped except when it is necessary to drive the pum. Where necessary wheel chocks blocks shall be used:
   

3. any driving units or electrical equipment not required and not specifically designed for the transfer operation shall be stopped or isolated ;
   

4.  the vessel mounted on a vehicle shall be electrically bonded to the fixed installation before any flammable liquefied gas transfer operation is carried out ;
   

5. before a vehicle is moved the electrical and the liquid and vapour connections shall be disconnected care being exercised to avoid spillage. Where wheel chock blocks have been used they shall be removed. The vehicle shall be checked to ensure that it is in safe working order and the surrounding areas checked to ensure that any liquefied flammable gas that may have leaked or has to be vented has safely dispersed.

5. For keeping attention during operations:

(i)                   a competent person shall remain in attendance during all the operations connected with the transfer and ensure that all the requirements of these rules are complied with ;

(ii)                 If it is necessary to discontinue a vehicle loading operation temporarily the loading hose shall be disconnected from the vehicle for the period of such discontinuance.

6. The person in charge if transfer operations shall ensure that transfer operations are stopped in the event of:

(i)                   any leakage ;

(ii)                  a fire occurring in the vicinity ;

(iii)                a severe electrical storm occurring in the vicinity in the case of an operation which involves venting of flammable gas. 

31.   Electrical apparatus and installations

1. no electrical wire shall pass over any storage vessel.
   

2. All electrical wires installed within safety zone or any storage vessel for the storage of flammable compressed gases shall consist of insulated cables of approved type. The cable shall be mechanically continuous throughout and effectively earthed away from the vessels.
   

3. For pumps rooms used for pumping flammable compressed gases :-

   (i)      all electrical metres distribution boards switches fuses plugs and sockets shall be of flame proof construction complying with the requirements of IS : 2148 :1968 and the frames shall be effectively earthed ;

   (ii)    all electrical fixed lamps should be enclosed in a well glass flameproof fittings conforming to IS :2206 (part I) 2962. 
   

4. All electrical portable hand lamps shall be of a type approved by the Chief Controller.

32.   Lighting of storage and operating areas

Operations shall not be carried out during the night unless adequate artificial lightings of approved type are available and used.

33. Certificate of safety

A certificate of safety in the proforma prescribed by the Chief Controller and signed by a competent shall be furnished to the licensing authority before shall be furnished to the licensing authority before any vessel is used for the storage of any compressed gas or whenever any addition or alteration to the installations or foundations for the vessel is carried out.