AWeld1
Computer
- Jul 21, 2014
- 22
Gentlemen,
We have proposed a Modification of Yard Drain with the concept to reroute the block HP drains into a 150mm diameter common line that connects to the block clean drains tank and to similarly reroute all the IP drains into a common 150mm diameter pipe that connects with the block clean drain tanks, it was commented that this is not allowed in ASME B31.1 section 122.
Thus, we were informed that “ unless we intend of providing stop valves for reach line and/or automatic valves that will prevent reverse flow in each line, [highlight #EF2929]ASME 31.1 section 122 requires that each trap discharge line should be a separate line of the same diameter as the drain connection (ASME B31.1 - 122.1.5) made from material capable of withstanding the pressure and temperature (ASME B31.1 – 122.11.2) and connected to the clean drains tank by its own connection as per the existing drain lines.[/highlight] Each line should have a flow of restriction orifice similar to that provided for all the other drain line connections to the clean drain tank.”
If we are to follow the below mentioned 122.1.5 Boiler Drains and requirements shall be met, is the comment (marked in red) considered to be applicable?
ASME 31.1 – 122.1.5 Boiler Drains:
A) Complete drainage of the boiler and attached piping shall be provided to the extent necessary to ensure proper operation of the steam supply system. The pipe, fittings, and valves of any drain line shall not be smaller than the drain connection.
(B) If the drain lines are intended to be used both as drains and as blowoffs, then two valves are required and all conditions of paras. 122.1.4, 122.1.7(C), and 122.2 shall be met.
(C) Miniature boilers constructed in accordance with the rules contained in the ASME Boiler and Pressure Vessel Code, Section I, Parts PMB and PEB may use a single valve where drain lines are intended to be used for both blowoff and periodic automatic or manual flushing prior to startup. The single valve shall be designed for blowoff service but need not have locking capability.
(D) When a drain is intended for use only when the boiler is not under pressure (pressurizing the boiler for rapid drainage is an exception), a single shutoff valve is acceptable under the following conditions: either the valve shall be a type that can be locked in the closed position, or a suitable flanged and bolted connection that accepts a blank insert shall be located on the downstream
side of the valve. When a single valve is used, it need not be designed for blowoff service. Single valves on miniature boilers constructed in accordance with the rules contained in the ASME Boiler and Pressure Vessel Code, Section I, Parts PMB and PEB do not require locking capability.
(E) Drain piping from the drain connection, including the required valve(s) or the blanked flange connection, shall be designed for the temperature and pressure of the drain connection. The remaining piping shall be designed for the expected maximum temperature and pressure. Static head and possible choked flow conditions shall be considered. In no case shall the design
pressure and temperature be less than 100 psig [690 kPa (gage)] and 220°F (105°C), respectively.
Thank you very much and hoping for a quick response regarding the matter.
We have proposed a Modification of Yard Drain with the concept to reroute the block HP drains into a 150mm diameter common line that connects to the block clean drains tank and to similarly reroute all the IP drains into a common 150mm diameter pipe that connects with the block clean drain tanks, it was commented that this is not allowed in ASME B31.1 section 122.
Thus, we were informed that “ unless we intend of providing stop valves for reach line and/or automatic valves that will prevent reverse flow in each line, [highlight #EF2929]ASME 31.1 section 122 requires that each trap discharge line should be a separate line of the same diameter as the drain connection (ASME B31.1 - 122.1.5) made from material capable of withstanding the pressure and temperature (ASME B31.1 – 122.11.2) and connected to the clean drains tank by its own connection as per the existing drain lines.[/highlight] Each line should have a flow of restriction orifice similar to that provided for all the other drain line connections to the clean drain tank.”
If we are to follow the below mentioned 122.1.5 Boiler Drains and requirements shall be met, is the comment (marked in red) considered to be applicable?
ASME 31.1 – 122.1.5 Boiler Drains:
A) Complete drainage of the boiler and attached piping shall be provided to the extent necessary to ensure proper operation of the steam supply system. The pipe, fittings, and valves of any drain line shall not be smaller than the drain connection.
(B) If the drain lines are intended to be used both as drains and as blowoffs, then two valves are required and all conditions of paras. 122.1.4, 122.1.7(C), and 122.2 shall be met.
(C) Miniature boilers constructed in accordance with the rules contained in the ASME Boiler and Pressure Vessel Code, Section I, Parts PMB and PEB may use a single valve where drain lines are intended to be used for both blowoff and periodic automatic or manual flushing prior to startup. The single valve shall be designed for blowoff service but need not have locking capability.
(D) When a drain is intended for use only when the boiler is not under pressure (pressurizing the boiler for rapid drainage is an exception), a single shutoff valve is acceptable under the following conditions: either the valve shall be a type that can be locked in the closed position, or a suitable flanged and bolted connection that accepts a blank insert shall be located on the downstream
side of the valve. When a single valve is used, it need not be designed for blowoff service. Single valves on miniature boilers constructed in accordance with the rules contained in the ASME Boiler and Pressure Vessel Code, Section I, Parts PMB and PEB do not require locking capability.
(E) Drain piping from the drain connection, including the required valve(s) or the blanked flange connection, shall be designed for the temperature and pressure of the drain connection. The remaining piping shall be designed for the expected maximum temperature and pressure. Static head and possible choked flow conditions shall be considered. In no case shall the design
pressure and temperature be less than 100 psig [690 kPa (gage)] and 220°F (105°C), respectively.
Thank you very much and hoping for a quick response regarding the matter.
