SHELL CONNECTIONS PAR 9.13 SVR_Part_4_e-Jan18.pdf

Part 4 Vessel Systems and Machinery Chapter 6 Piping Systems Section 2 Metallic Piping 4-6-2

9.9.3 Relief Valve Discharges

For systems conveying flammable liquids or gases, relief valves are to be arranged to discharge back to the suction side of the pump or to a tank. The relief valve of a CO2 system is to discharge outside of the CO2 container storage compartment. In all cases, when discharging directly to the atmosphere, the discharge is not to impinge on other piping or equipment and is to be directed away from areas used by personnel.

9.9.4 Setting

Relief valves are to be set at pressures not exceeding the piping design pressure. For hydraulic systems, see 4-6-7/3.7.2; for steering gear hydraulic piping systems, see 4-3-4/9.1.6.

9.9.5 Pressure Vessels Associated with Piping System

A pressure vessel, which can be isolated from piping system relief valves, is to have another relief valve fitted either directly on the pressure vessel or between the pressure vessel and the isolation valve.

9.11 Temperature and Pressure Sensing Devices

9.11.1 Temperature

Where thermometers or other temperature sensing devices are fitted in piping systems, thermometer wells are to be used so that the devices can be removed without impairing the integrity of the pressurized system.

9.11.2 Pressure

Where pressure gauges or other pressure sensing devices are fitted in piping systems, valves are to be provided so that the devices can be isolated and removed without impairing the integrity of the pressurized system.

9.11.3 Tanks

Pressure, temperature and level sensing devices installed on tanks at locations where they are subjected to a static head of liquid are to be fitted with valves or arranged such that they may be removed without emptying the tank.

9.13 Shell Connections

9.13.1 General (2016)

Positive closing valves are to be fitted at the shell at inlets (including sea chests) and discharges.

Discharges from scuppers and drains are to be fitted with valves as required by 4-6-4/3.3. Where it is impractical to install the valve directly at the shell, a distance piece can be provided. Materials readily rendered ineffective by heat are not to be used for connection to the shell where the failure of the material in the event of a fire would give rise to danger of flooding. Discharges at the shell are to be so located as to prevent any discharge from falling onto a lowered lifeboat or rescue boat.

9.13.2 Valves

Shell valves are to comply with the following requirements:

i) Gray cast iron valves are not to be used as shell valves. Nodular iron valves are acceptable, see 4-6-2/3.1.4.

ii) Shell valves are to be installed such that the inboard piping can be removed and the valve can remain in place without impairing the watertight integrity. Wafer-type butterfly valves are not acceptable. Butterfly valves with lugs, however, may be accepted.

iii) Controls for positive closing valves are to be readily accessible and controllable from the floors or gratings. Open or closed indicators are to be provided, see 4-6-2/5.11.3(a).

iv) Power-operated valves are to be arranged for manual operation in the event of a failure of the power supply.

v) For hydrostatic tests, see 4-6-2/7.3.2.

ABS RULES FOR BUILDING AND CLASSING STEEL VESSELS . 2018 419

Part 4 Vessel Systems and Machinery Chapter 6 Piping Systems Section 2 Metallic Piping 4-6-2

9.13.3 Connection Details (2015)

Where the valve is connected directly to the shell, studs can be used if a reinforcing ring of substantial thickness (a heavy pad) is welded to the inside of the shell. In this case, the studs are to be threaded into the reinforcing ring and are not to penetrate the shell.

Where a distance piece is fitted between the shell and the shell valves, the pipe is to be of steel and of wall thickness not less than that specified in 4-6-4/3.3.5(a).

In general, the pipe is to be as short as possible. The pipe is to extend through the shell plating and is to be welded on both sides or with full strength welds from one side. Consideration is to be given to supporting the pipe to the surrounding structure.

Where an inlet or discharge is to pass through a wing tank or a cargo hold, the valve may be installed on the inner bulkhead or similar location provided that the pipe between the valve and the shell is of wall thickness not less than as specified above, with all joints welded and with built-in provision for flexibility. Such pipes, where located in a cargo hold, are to have protection from mechanical damage.

Threaded connections are not considered an acceptable method of connection outboard of the shell valves.

9.13.4 Boiler Blow-off

Boiler and evaporator blow-off overboard discharges are to have doubling plates or heavy inserts fitted. The pipe is to extend through the doubling and the shell.

9.13.5 Sea Chests

Sea chests are to comply with the following requirements:

i) Located in positions where the possibility of blanking off the suction is minimized;

ii) Fitted with strainer plates through which the clear area is to be at least 1.5 times the area of the inlet valves;

iii) Means are provided for clearing the strainer plates, such as by using compressed air or low pressure steam;

iv) Additional requirements for sea chests on ice strengthened vessels in 6-1-3/17, 6-1-4/23.13, 6-1-5/45.13, and 6-1-6/29.3 are to be complied with, where applicable.

9.15 Control of Static Electricity (2014)

In order to prevent dangerous build-up of static charges resulting from the flow of fluid in piping, the following items are to be earthed (grounded) to the hull such that the resistance between any point on the piping and the hull (across joints, pipe to hull) does not exceed 1 MΩ:

• Piping and independent tanks containing fluids having flash point of 60°C (140°F) or less.

• Piping that is routed through hazardous areas.

This can be achieved if the items are directly, or via their supports, either welded or bolted to the hull.

Bonding straps are required for items not permanently connected to the hull, for example:

• Independent cargo tanks

• Piping which is electrically insulated from the hull

• Piping which has spool pieces arranged for removal

• Wafer-style valves with non-conductive (e.g., polytetrafluoroethylene PTFE) gaskets or seals

Bonding straps are to be:

• Installed in visible locations

• Protected from mechanical damage

• Made of corrosion-resistant material

420 ABS RULES FOR BUILDING AND CLASSING STEEL VESSELS . 2018

Steven Dzitko Highlight

Steven Dzitko Highlight