Transfer of steam from boiler to the point of steam use is the most common need in the dairy plant. Steam is transported in thicker walled conduits known as pipes.
Steam pipelines are different from sanitary pipes used in dairy plant. The sanitary pipe and fittings refers to the stainless steel tubing used for transportation of milk and milk products. These sanitary pipe fittings have sanitary design features, such as, ease in assembling and dismantling, smooth polish finish both inside and outside and hygienic characteristics to avoid product contamination. These types of pipelines are discussed separately
The material of construction of steam pipes is mild steel (MS). Mild steel is iron with low carbon content. Steam lines are subjected to pressure as well as thermal stresses and require extra care. The most important factors, which govern the design and installation of steam lines, are : pipe size, pipeline support system,alignment, drainage of condensate from steam lines and adequate insulation cover.
a) Pipe size: a pressure drop accompanies Flow of steam through a pipe. Steam pipeline must be of proper size to carry the steam load requirement without undue pressure drop.
b) Pipeline supports: Various types of pipe support systems are used in a dairy plant. The pipes may be supported from the ceiling for single, double or multiple lines. It may be supported from the walls by means of brackets. Whether the support is from ceiling or from walls, flange type plates are fixed firmly into ceiling or the walls. The tubes,which are used to support the structure, are welded to these plates and the pipe lines are placed over the support structure. Pipe supports should be spaced closely enough to prevent undue sag in the span.
c) Alignment: Poor alignment of piping is the frequent cause of leaks in pipe line joints. Leaks are also there if the joints are not designed or supported properly.Hence the pipe line is precisely aligned with due respect to all the bends and joints at the time of installation. Proper support is provided at the joints. Piping is always supported on both sides of every large valve. Screwed or the expanded type flanges are used at the joints on steam pipe lines for pressures up to 3000kPa and temperatures up to 672 K. For higher pressures and temperatures the welded type flanges are used.
d) Drainage of condensate in the pipe line: As the steam flows through the pipes some condensation usually occurs. If the steam condensate is not drained out of the steam pipe it accumulates at the pockets in the pipe line. Whenever the valve in the line is opened, this accumulated water moves in a column. The sudden movement and stoppage of this water column in the pipe line results in
water hammer. If a steam pipe is constantly hammered it is damaged. Proper drainage of condensate from the steam pipe line is thus of utmost importance.For self draining of condensate a slope of 0.25 to 0.3 % is given to the steam pipe line in the direction of steam flow. A full bore Tee (Equal Tee) is used for trapping the condensate from the line and lead it to the traps located at vulnerable points. Any sag in the pipe line is undesirable as it would result in condensate pocket. The sag in the pipe is removed by proper spacing between pipeline supports.
e) Pipeline insulation: To prevent heat losses from the steam pipe lines, the pipes are insulated. The pipe insulation cover is also known as lagging. The common insulating materials used are Asbestos sponge felt, Magnesia or asbestos hair or glass wool.
An ideal piping system is that in which each part is self supported and imposes no stress on the other part. All elements in the system hold their correct relative positions and alignment despite thermal expansion and contraction. Anchors are used to fix certain points of the system, and expansion bends, joints and supports are provided for free movement for all the rest of the piping in the system. Anchors are designed to securely lock the anchored points in the piping to heavy steel or concrete work. Steam line is properly pitched for condensate drainage. It is ensured that sag in the pipe, if there is any, does not result in the centre point of span between two supports below its lower support, and otherwise it would form a condensation pocket that may lead t water hammer.
Steam pipelines are different from sanitary pipes used in dairy plant. The sanitary pipe and fittings refers to the stainless steel tubing used for transportation of milk and milk products. These sanitary pipe fittings have sanitary design features, such as, ease in assembling and dismantling, smooth polish finish both inside and outside and hygienic characteristics to avoid product contamination. These types of pipelines are discussed separately
The material of construction of steam pipes is mild steel (MS). Mild steel is iron with low carbon content. Steam lines are subjected to pressure as well as thermal stresses and require extra care. The most important factors, which govern the design and installation of steam lines, are : pipe size, pipeline support system,alignment, drainage of condensate from steam lines and adequate insulation cover.
a) Pipe size: a pressure drop accompanies Flow of steam through a pipe. Steam pipeline must be of proper size to carry the steam load requirement without undue pressure drop.
b) Pipeline supports: Various types of pipe support systems are used in a dairy plant. The pipes may be supported from the ceiling for single, double or multiple lines. It may be supported from the walls by means of brackets. Whether the support is from ceiling or from walls, flange type plates are fixed firmly into ceiling or the walls. The tubes,which are used to support the structure, are welded to these plates and the pipe lines are placed over the support structure. Pipe supports should be spaced closely enough to prevent undue sag in the span.
c) Alignment: Poor alignment of piping is the frequent cause of leaks in pipe line joints. Leaks are also there if the joints are not designed or supported properly.Hence the pipe line is precisely aligned with due respect to all the bends and joints at the time of installation. Proper support is provided at the joints. Piping is always supported on both sides of every large valve. Screwed or the expanded type flanges are used at the joints on steam pipe lines for pressures up to 3000kPa and temperatures up to 672 K. For higher pressures and temperatures the welded type flanges are used.
d) Drainage of condensate in the pipe line: As the steam flows through the pipes some condensation usually occurs. If the steam condensate is not drained out of the steam pipe it accumulates at the pockets in the pipe line. Whenever the valve in the line is opened, this accumulated water moves in a column. The sudden movement and stoppage of this water column in the pipe line results in
water hammer. If a steam pipe is constantly hammered it is damaged. Proper drainage of condensate from the steam pipe line is thus of utmost importance.For self draining of condensate a slope of 0.25 to 0.3 % is given to the steam pipe line in the direction of steam flow. A full bore Tee (Equal Tee) is used for trapping the condensate from the line and lead it to the traps located at vulnerable points. Any sag in the pipe line is undesirable as it would result in condensate pocket. The sag in the pipe is removed by proper spacing between pipeline supports.
e) Pipeline insulation: To prevent heat losses from the steam pipe lines, the pipes are insulated. The pipe insulation cover is also known as lagging. The common insulating materials used are Asbestos sponge felt, Magnesia or asbestos hair or glass wool.
An ideal piping system is that in which each part is self supported and imposes no stress on the other part. All elements in the system hold their correct relative positions and alignment despite thermal expansion and contraction. Anchors are used to fix certain points of the system, and expansion bends, joints and supports are provided for free movement for all the rest of the piping in the system. Anchors are designed to securely lock the anchored points in the piping to heavy steel or concrete work. Steam line is properly pitched for condensate drainage. It is ensured that sag in the pipe, if there is any, does not result in the centre point of span between two supports below its lower support, and otherwise it would form a condensation pocket that may lead t water hammer.
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