HOT WATER TANKS (HLW STAMP)
Hanson lined potable hot water storage tanks are built and tested in accordance with the A.S.M.E. Boiler and Pressure Vessel Code Section IV, HLW, for unfired pressure vessels and bear the “HLW” stamp, National Board number and Manufacturer’s serial number, as required. A copy of the A.S.M.E. data sheet HLW-6, signed by an A.S.M.E. authorized inspector, will be sent with the invoice if requested at time of order.
Vessels built in accordance with this section of the ASME Code are limited to a maximum working pressure of 160# and a maximum temperature of 210oF.
For access to the inside of an HLW tank to line it, we install an 11″ x 15″ opening, which can also serve as an inspection port when the tank is in service. It is labeled as a “handhole” on our shop drawing. The second inspection opening that the Code requires is usually a plugged 2″ tapping, the minimum size allowed.
As the ASME definition of a “manway” is an opening with an effective minimum size 12″ x 16″, anything smaller cannot be so labeled per Code.
Many local jurisdictions mandate a minimum clearances in front of a tank manway in service. Whether an 11″ x 15″ handhole/inspection opening is determined to be a manway for clearance purposes is at the discretion of the local inspector responsible for approving the installation.
Water tanks for other than potable hot water service (expansion, hydropneumatic, chilled, deareator, blowdown etc.) are manufactured to A.S.M.E. Section VIII Division I, and bear a “U” stamp. These are built to order.