CARGO HOSES ON CHEMICAL TANKERS – CAPT AJIT VADAKAYIL
Parcel chemical tanker cargo hoses are usually made of Polypropelene.
They are composed of multiple layers of polypropylene films and fabrics, reinforced with inner and outer spiral wire helixes. A polar fluid resilient barrier is an integral part of the hose construction. The inner , outer wires and wire helix is SS. The outer cover is weather and abrasion resistant PVC impregnated polyster fabric. This construction results in a light and flexible hose.
Type approvals are from IMO, USCG and all major Classification societies. Each hose is individually serialized and delivered with its own test certificate. Both inner and outer wires are connected to each other and must be tested for continuity. The temperature range is from -30C to 100C.
End Stainless Steel ASA/ DIN/ TTMA flanges are attached by external swage method. Use one nylon choker hitched flat sling for every 15 feet of hose.
Hoses must be stowed with respect in a sheltered place at the manifold .
Cargo hoses must be cleaned after use and always before testing or prolonged storage. Preferably, the initial cleaning should be carried out while hoses are connected between the tank being washed and the slop tank.
Hoses being fresh water rinsed, sprayed with Methanol, Acetone, Methyl Ethyl Ketone, etc., must be vertically hung to facilitate proper drainage of the rinsing medium . When hoses are disconnected and the cargo being transferred is considered an "easy cargo", only fresh water rinsing or live steaming may be sufficient as final cleaning.
Steaming of hoses must be done in a vertical position. When cargo hoses are live steamed in a horizontal position, cargo residue is not easily removed from the inner-lining .The condensation which washes down must be collected in a clear glass sample bottle and tested for clarity, pH etc.
Hoses must be electrically earthed to prevent static charge build-up, especially when live steamed near flammable areas They must be stowed with both ends blanked. When applying live steam, the steam hose must be flanged to one end of the cargo hose and leaving the other end unflanged. The steam hose should be "free steamed" before connecting it to a cargo hose to assure its cleanliness.
Cargo hoses with limited heat resistance must be live steamed for short periods only. During live steaming, the hoses cannot be exposed to temperatures exceeding the maximum recommended by the manufacturer.
Polypropelene hoses are destroyed by excess heat and UV of sunlight. Hoses must not be kinked . Hoses must be hung from their flanges when lifting by crane.
An ideal hose cradle will have a camber in fore and aft direction so that the middle part of the hose is higher than the flanges by say 2 feet for self draining. The cradle must not have any metal to prevent galvanic corrosion to the out spiral wire. There must be recessed grooves to prevent the hose from turning and twisting during rolling. Needless to say that the cradle must be within easy reach of the manifold crane.
Have Insulation must be checked when dry. Resistance should not exceed 6 ohms per metre length.
Their markings must be reconciled with their certificates and manufacturers resistance suitability. If the certificate number is not on the flange punch it on an SS tag and attach it to the hose or atleast paint it.
The hoses nust be numbered . This way you are able to maintain the last 3 cargoes handled by them, whether it handles Tallow or MEG fibre grade.
If stainless steel hoses are used for discharge of Sulphuric acid they must be replaced by non SS acid resistant hose before cleaning starts. For Sulphuric acid in 30 to 70% concentration is non oxidising and attacks SS rapidly , particularly at high temperatures.
Pigging of cargo hose is never done.
Hoses must be electrically earthed to prevent static charge build up.
Prior every use the hose must be visually inspected for kinks, bulges, soft spots and cuts that penetrate the first layer of hose reinforcement. Don’t allow the hoses to roll from port to stbd when the ship is rolling. Hoses must never be allowed to touch steam pipes. When discharging to barges at anchorage make sure hoses are not chafed by ships movement.
If it chafes put a chafing pad for protection. At the manifold hoses should be supported by flat saddles at, at least 2 points. No rope is to be used direct on hose. Slight carelessness and hose has to be discarded, and these hoses cost lot of money. The hoses must not be bend at a radius less than recommended by the manufacturer.
Cargo hoses should not be allowed to come into contact with a hot surface such as a steam pipe. Protection should be provided at any sharp corner or point where chafing or rubbing can occur. The use of steel wires strops in direct contact with the hose cover is not be permitted.
Hoses should not be lifted at a single point with ends flanges hanging down but should be supported so that they are not bent to a radius less than that recommended by the manufacturer. Excessive weight on the ship's manifold should be avoided--the hose string should be supported by bridles or saddles. Use only flat straps
Do not accept new hoses if they do not come with hose manufacturers certificate and hose resistancy booklet. Keep an annual test record as per company form.
A prototype is tested to 5 times design pressure. Working pressure is 1/5 of bursting pressure. Once in service hoses are tested to 1.5 times WP but not more than 2/5 of bursting pressure. Our Company policy is to test hoses every 12 months. Test pressure is 125% of working pressure once in service. The working pressure of the hose should be greater than 10 bars. You must keep a record of elongation suffered by the hose after testing.
AS PER USCG 46 CFR 153.940 the minimum bursting pressure should be 52.7 kg/cm2 or 750 psi. the max allowable working pressure is 10.5 gk/cm2 or 150 psi and cannot be greater than 1/5 of bursting pressure.
The IMO IBC code papa 2.12 allows burst pressure to be 5 times the service pressure. With a usual service pressure of no more than 120 psi ( 8.4 kg/ cm2) this works out to 600 psi (42 kg/ cm2). Remember the higher USCG requirements apply .
When closing valves, a vacuum might be created in cargo hoses. The vacuum created may cause the hoses to collapse if not carefully dealt with.
During cargo transfer is the hose bulges or kinks, the transfer must be stopped and hose replaced.
The loading hose must allow for vessels anticipated movements at berth due to wind , tide, draft/ trim change
Hose bend radius in must never less than 12 times the hose diameter.
The hose must be non collapsible to prevent kinking
Jumper hoses at manifold must be properly supported –and also corners must be padded
IDENTIFICATION AND MARKING OF CARGO HOSES
A. Each hose should be stencilled with a consecutive two-digit number.
B. Cargo hose test certificates, factory test certificate of new hoses and other relevant papers, should be filed properly in a dedicated file.
C. Each hose to be marked by a contrasting and wear-resistant paint as follows:
TESTED TO 150 PSI, on date DEC/14/09
D. U.S. Coast Guard Regulation 33 CFR, Parts 154 and 155 now additionally requires that the hose be marked with a list of products for which it certified for use.
Due to the fact that hoses supplied are multi-purpose chemical hoses, this will not be practicable. They will therefore be identified with a stainless steel tag strapped to the hose by S.S. bandit tape.
E. The Label indicates that hose is for use with "Hazardous Materials-Chemicals" (HAZMAT SERVICE-C), however the makers compatibility list must be consulted prior to cargo operation and no unmarked hose is to be used.
F. It is essential that the vessel maintains accurate records of the following which must be available for inspection at any time by the terminal or regulatory authorities:
1. Original Makers Test Certificate.
2. Makers Compatibility List.
3. Vessel's records of Last Onboard Pressure Test.
G. Hoses must be inspected prior to being used for every cargo operation and logged. Damaged hoses must be stowed elsewhere and marked boldly --out of use—damaged.
Hose Pressure requirements 46CFR 153.940
Minimum bursting pressure *750 psig (52.7 kg/cm2); (2) 5 times MAWP)
Maximum allowable working pressure
(1) at least 150 psig (10.5 kg/cm2)
(2) not more than 1/5 of bursting pressure.
Note: The IMO Bulk Chemical Code would allow the burst pressure to be 5 times the "service pressure". With a usual "service pressure" of no more than 120 psig (8.4 kg/cm2), this works out to 600 psig (42 kg/ca2). The higher USCG requirements thus apply for chemical hoses.
• Hose Manufacturer's Certificate - should be delivered with all new hoses.
• Hose manufacturer's resistancy booklet.
• Annual test record book.
Hoses should not be twisted to achieve bolt hole alignment. Hoses to be connected with considerable slack, also the hose should be so set that the curvature occurs over the full length of the hose, as far as possible. Hoses must be completely drained prior commencement of disconnection.
Stencil MAWP of 15 Bars . TESTED on date--- , on cargo hose as per USCG California regulations. Keep cargo hose certificates and Chemical resistance tables together in one file.
Note down the serial numbers punched on the hose flange.
Below: Ship's manifold
Below: Ship's manifold
Note: Ships chemical hoses for internal manifold looping are NOT the same a shore HD hoses used in shore Annex 1 terminals-- ( for example the insulation resistance test requirement is different..)
Below : Shore terminal hose .
Below : Shore terminal hose .
CAPT AJIT VADAKAYIL
30 years in command.