Correction slip 7 of IRSOD 2004 espouses a minimum electrical clearance of 270 mm of Rolling Stock from the contact wire.

In many cases, soapy water must be used to locate liquid leaks because they are not readily visible. The white fog of its discharge can distinguish LPG while liquid can only be distinguished by careful viewing.

DO NOT TAKE THE PLUG OUT FOR LAPPING OF THE THREAD. If the plug is removed when leakage is present, liquid will probably be discharged with a consequent extreme hazard.

If there is leakage around safety valve, first check whether the valve is merely performing its function (relieving excess pressure). However, if considerable flow is evident, isolate and notify oil company.

Additional stiffener plates provided on the top of centre sill and above the back portion of CBC to avoid the lifting of CBC and hitting of barrel.

A magnet at the bottom of filling pipe is provided to arrest foreign items such as nut, bolt & locking wire etc. to avoid damage to the seat of master valve.

All these valves should be tested on a bench by applying hydraulic pressure by means of a pump.

In view of the possibility of pilferage/damage, the pressure gauge should be removed before releasing the tank wagon.

The main fittings are two liquid education valves, a vapour education valve, a safety valve, a slip tube for determining liquid level, a pressure gauge, a thermometer well and excess flow valves.

Most of these valves and fittings are specialized pieces of equipment, made of special materials. Substitution by components made of incorrect materials or to wrong tolerances could have undesirable repercussions.

V rings are pressure seals, which expand on application of pressure to remain leak proof.

Asbestos packing or rubber packing is commonly used depending upon the type of vessels and commodity carried.

Changing of resilient seals of liquified petroleum gas tank wagons, when the vessel is under pressure within 10 pounds of the operating pressure of the valves, should not be attempted.

Since deteriorated seals and dirt on the seals are the most frequent cause of leakage, the seals should be given careful attention.

The safety valve adjustment should not be interfered with unless repairs to the valve become necessary or the valve operates incorrectly.

The safety valve should be given a pneumatic test. It must be vapour tight against leakage at specified pressures.

After every interruption of the arc, welding should be restarted ahead of the previous deposit and then moved back to fill the crater before proceeding forward again.

It must be ensured that the let-in patch is of the same material and thickness as the parent metal.

It is preferable if the welding is done from the inside of the barrel and is in the down hand/horizontal position.

A 12mm dia hole should be drilled at the ends of the crack and the full length of the crack should then be carefully chipped and C grooved for welding.

When pits are in a close group or in one straight line and are deep enough to affect strength, the affected area should be cut out and replaced with a let-in patch.

Pits when not deep enough to affect the strength of the parent plate may be chipped to sound metal, welded and then ground flush to the original thickness.

A workshop undertaking such repairs must be properly equipped and facilities for radiographic examination of the repaired joints must be available.

Pressure vessels requiring repairs should be inspected by a competent authority approved by Chief Controller of Explosives.

The plate should be struck at intervals of about 6 inches for the whole length of all main welded seams.

The weight of the hammer should not exceed 5 Kg.

The hammer should be of a material softer than the barrel plate and its edges so rounded as to prevent denting of the barrel plates.

In case of leakage, the pressure should be reduced by 20%. The lagging and insulation is removed for locating leaks.

Valves are tested in two ways: with valves closed and outlet cap off, and with valves open and outlet cap in position.

Connection is to be made through a dummy flange with pressure gauge attached, fitted on the safety valve seating.

The tank barrel should be tested by using a power driven hydraulic pump which should enable a steady increase of pressure in the tank barrel.

The barrel should be vented to prevent formation of air pockets while it is being filled.

If the examination indicates that the corrosion/erosion has taken place to such an extent that the barrel is likely to rupture during hydraulic test, first carry out the repairs and then give a hydraulic test.

The barrel should be examined by a competent inspector nominated by the CME, who must examine the interior of the barrel and the internal fittings.

It is necessary to inspect the barrel before hydraulic test so as to avoid accidental rupture of corroded barrel plates at the time of hydraulic test.

A clean bottle filled with fresh water is lowered through the manhole. A string is attached to the bottom of the bottle before lowering.

In Nessler's test, the reagent used is a solution of potassium mercuric iodide with potassium hydroxide. This reagent gives a brown colour when mixed with water containing ammonia.

The steam pipe should be provided with a "T" connection at its lower end and so directed as to blow steam towards both ends for thorough cleaning.

The first step is to remove the manhole cover together with manhole housing, valves etc. and leave the tank exposed to atmosphere for few hours.

Blank flanges are used with 2mm compressed asbestos fiber jointing material to IS:2712-65.

The bottom discharge valve openings are provided with blank flanges to serve as a further check on accidental leakage of contents.

For LPG tank wagons, the start of discharge pressure for safety valve is above 15.85 Kg/cm².

For Ammonia tank wagons, the start of discharge pressure for safety valve is above 22.15 Kg/cm².

For Petrol tank wagons (BTPN/BTFN), the safety valve is located outside the dome.

For Ammonia tank wagons (BTAL/BTALN), the safety valve is located inside the dome.

According to Table 9.2, LPG tank wagons (BTPGL/BTPGLN) have TWO safety valves.

According to Table 9.2, Ammonia tank wagons (BTAL/BTALN/BTALNM) have ONE safety valve.

For Petrol tank wagons type BTPN, the dished ends use IS:5986 Fe360 Cu.

For LPG tank wagon type BTPGLN, the dished ends use Steel to BS:1501-224-Gr32 A LT 30 or ASTM-516 Gr. 70.

For Ammonia tank wagon type BTALN, BTALNM, the dished ends use Steel to BS:1501-224-Gr.32 A LT 50 or ASTM-516 Gr.-70.