• Free-cutting brasses, especially brasses that contain lead. One example of such brass is copper alloy
C36000 called free-cutting yellow brass.
• High lead brasses are especially a concern because of stress corrosion cracking when subjected to high
tensile stress.
• Steels that are not stainless steel.
• Stainless steels that are not properly solution treated.
The following materials are preferred:
• Copper alloys:
– Lead-free copper alloys with less than 15% zinc.
• Stainless steels:
– Low carbon stainless steels are preferred.
– Must be solution that is treated. Stainless steel that is solution-treated undergoes a specic heat
treatment to improve its resistance to corrosion.
– Passivation is desirable as long there is low possibility of acid entrapment in crevices.
– Avoid sensitization during welding.
– Avoid brazing; welding is preferred.
• Polyvinyl chloride (PVC) (not allowed inside IBM products due to flammability concerns, but can be
used at a facility level. Appropriate authorities that have jurisdiction must be consulted).
• EPDM rubber is the preferred material for hoses:
– Flammability rating must be CSA or UL VW-1 or better.
– Peroxide cured hoses are preferred because they do not absorb triazoles.
Metal joining operations:
• Solder joints that come in contact with water must be avoided. Solder joints are porous and they leach
flux residue into the cooling loop. Solder joints might pass inspection and pressure tests as
manufactured, but still might be unreliable.
• Brazed joints are preferred for joining copper plumbing pieces.
• Braze joints must not be used to join stainless steels. Tungsten inert gas (TIG) and metal inert gas (MIG)
welding are preferred for joining stainless steels. Sensitization must be avoided. Welded assembly must
be cleaned and, if possible, passivated if there is a low possibility of acid entrapment in crevices.
Deionizing equipment
Deionizing equipment is optional. It is recommended for use in large cooling loops. When the water needs
to be deionized, some of the water can be bypassed to flow through the deionizing cartridge.
Dosing Equipment
The following equipment is used to dose the cooling loop:
• Recommend using a stainless steel or berglass chemical shot feeder.
• System volumes less than 378.5 liters (100 gallons) use a 0.38 liter (0.1 gallon) size feeder
• System volumes less than 3875 liters (1000 gallons) use a 3.8 liter (1 gallon) size feeder
• System volumes greater than 3875 liters (1000 gallons) use a 9.5 liter (2.5 gallon) size feeder.
• Chemical pump according to Nalco or another water treatment contractor specication.
Monitoring equipment
The following equipment is used to monitor the cooling loop:
Racks and rack features
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