Compressed Air Piping Recommendations for Compressor ...

1 Hitachi Industrial Equipment WHITE PAPER. White Paper: Ambient Air's Impact on Compressed Air system Performance Compressed air Piping systems are complex and require careful planning. Compressed Air Piping Recommendations for Compressor Discharge and Plant Distribution By Nitin G. Shanbhag, Senior Manager, Air Technology Group, Hitachi America Compressed air Piping I. Piping MATERIAL 99 (National Fire Protection system designers face many SELECTION AND Association) Standard is used for challenges to designing systems Recommendations healthcare facilities. Compressed without pressure losses and BY USE air Piping materials can be divided contaminants. This paper will into two basic types: metal and review Piping material selections, Consult federal, state and local non-metal. Non-metal pipe is distribution and Compressor codes before deciding on the commonly called thermoplastic discharge Piping guidelines, type of Piping to be used.

2 For pipe. In our experience, and the basic causes of pressure industrial plants, ASME thermoplastic should be used losses in Compressed air Piping is the reference standard, while only in some air Compressor inlet systems. the latest version of NFPA Piping situations, which are not 1. Hitachi Industrial Equipment WHITE PAPER. White Paper: Ambient Air's Impact on Compressed Air system Performance may be shorter downstream of the air Compressor . Copper Piping Copper pipe is a common selection for sensitive Compressed air systems and when correctly sized and connected is very durable and effective. Type M hard, type L. hard and type K soft copper has a working pressure of 250 psig (17 bar). Type K hard copper Extruded aluminum alloy Piping is corrosion resistant, mechanically strong and easy to install.

3 Is rated for 400 psig (27 bar). Copper Piping is resistant to part of the scope of this paper. and extruded aluminum alloy, high temperatures with limits Metal pipe can be black iron, it is much heavier and harder to rated at 400 F (204 C). Even if copper, stainless steel work with-significantly increasing copper does fail, it will do so in a or extruded aluminum alloy. installation time. predictable manner with the pipe ends separating. Never join pipes Many engineers select galvanized or fittings by soldering. Lead- Black Iron Piping tin solders have a low ultimate inlet Piping for 100 psig (7 bar). Black iron Schedule 40 Piping Piping systems. This pipe coating strength, a low creep limit and in Compressed air systems is does help black iron inlet Piping depending on the alloy, start commonly used due to price and resist corrosion better than melting at 361 F (183 C).

4 Silver durability. Pipe diameters of 3" standard Schedule 40 pipe. Over and hard soldering are forms and below are normally threaded time, however, when corrosion is of brazing and should not be while larger diameter headers present, the galvanizing material confused with lead-tin soldering. use welds and flanges. Black peels off. The inlet Piping now Silver and hard soldering is iron pipe, however, will corrode becomes a source of potentially brazing with a silver alloy type when exposed to condensed destructive contaminants able of filler material, which melts moisture with the resulting to affect the mechanical integrity in the range of 1145-1800 F. solid particulates becoming a of the air Compressor . The (618-982 C). major source of contamination. same holds true for galvanized Internal corrosion becomes even air Compressor discharge and Extruded Aluminum more significant when exposed distribution Piping .

5 Often, Alloy Piping to the aggressive high-acid due to the aggressive acidic characteristics of some types of Extruded aluminum alloy characteristics of condensate, condensate. Compared to copper Compressed air Piping has the life of the galvanized coating 2. Hitachi Industrial Equipment WHITE PAPER. White Paper: Ambient Air's Impact on Compressed Air system Performance become very popular. It is very assembly and subassembly while black iron requires three resistant to corrosion and is production areas. Aluminum alloy (weld, fill and cover). Stainless lightweight allowing for easier can be installed or removed with steel normally does not seal installation. A lack of internal no skilled labor or soldering and well when threaded, performing corrosion translates into a smooth has a broad range of temperature much better with grooved type inner surface reducing pressure ratings from 4 to 176 F (15-80 C).

6 Connections. losses due to friction. Other Note that these ratings will vary characteristics offering better air from brand to brand. Air Compressor handling include internal flush Discharge Piping connections and inside diameters Materials Stainless Steel Piping the same size as the pipe size Schedule 10 stainless steel is Discharge air temperatures rating. Type K 4" copper pipe, lightweight (compared to black from centrifugal, reciprocating in contrast, has a " internal iron) and is corrosion resistant. and oil-free rotary screw air diameter. Another important Because it is easy to handle, it compressors can range from 250- feature of aluminum alloy is will normally have lower handling 350 F (121-177 C). Discharge the enhanced flexibility of the costs but skilled labor will be air temperatures from lubricated connections allowing for a required for welding.

7 For welded rotary screw air compressors can Piping system to easily adapt to connections, stainless steel range from 200-220 F (93-105 C). an industrial plants ever-changing usually requires just one bead Even if the air Compressor has Table 1: Piping Material Features and Characteristics Extruded Aluminum Piping Features Stainless Steel Black Iron Copper Alloy Schedule 10 Schedule 40. Light Light Weight Lighter Heavy Corrosion Resistant Yes No Yes Yes Vulnerable to Friction- No Yes No No generated Pressure Loss Mechanical Strength Very Strong Very Strong Strong Strong High Temperature Rating Yes Yes Yes Yes Installation Ease Less Difficult Difficult Less Difficult Easy Installation Cost 30% / 70% 25% / 75% 40% / 60% 80% / 20%. Material%/Labor%. Special Tools Required Some (welder, threader, groove Yes Yes No (solder).)

8 Cutter). 3. Hitachi Industrial Equipment WHITE PAPER. White Paper: Ambient Air's Impact on Compressed Air system Performance Distribution Piping Materials The objective for feeder Piping and the drops is to deliver the maximum amount of flow to the work-stations or process with minimum pressure loss and zero contaminants. Piping materials vulnerable to corrosion, extended across an entire factory, can add significant volumes of solid particulate contaminants able to create pressure loss and potential production issues. Here again, this paper recommends stainless steel Piping or proper extruded Air receivers reduce pulsations, separate moisture and act as a reservoir for sudden air demands. aluminum alloy materials over black iron or copper. an after-cooler, considerations They will resist corrosion much should be given to what happens better than the standard Schedule if the after-cooler fails.

9 Piping 40 black iron and copper Piping . II. DISTRIBUTION. materials must therefore be able Due to connection flexibility and Piping INSTALLATION. to withstand these temperatures installation costs, aluminum alloy GUIDELINES. along with oil and condensed is recommended over stainless moisture, which may be highly steel in Piping diameters of less Piping systems have many acidic. than 8 inches (203 mm). variables to take into account. These include vibration, The main objective of discharge Some common air Compressor pulsations, temperature exposure Piping is to deliver Compressed discharge Piping installation best (internal and external), maximum air to the filters, dryers, receiver practices include: air pressures, corrosion and tanks and distribution headers chemical resistance. In addition, contaminant-free and with little or Upset to larger pipe than the lubricated compressors will no pressure-loss.

10 The objective discharge flange opening always discharge some oil into the should be a 0 psi Piping header Use stainless steel wire air stream, and the compatibility pressure drop! flexible connectors of the discharge Piping and other Pipe support to the floor accessories (such as o-rings and This paper recommends using seals) with both petroleum and/. No weight on the Compressor stainless steel or proper extruded or synthetic lubricants is critical. flange aluminum alloy over black iron. Pressure drop between the air 4. Hitachi Industrial Equipment WHITE PAPER. White Paper: Ambient Air's Impact on Compressed Air system Performance receiver is such that the air does not stagnate. Air flow should go into the bottom of the receiver and come out the top whenever possible. The entrance and exits should be at right angles near or on the same plane.