Welders at Allentown Metal use a Tempilstik for pre- and post-heat determination as they work, to stabilize the material. It provides precisely calibrated measurements for inspection and documentation.

Every job has its new aspects. Sometimes new qualifications and preliminary testing and development of procedures have to be established in-house before final fabrication can begin. Sometimes the fabricator has to provide mockup procedures and prototype fabrication to be evaluated by the customer’s engineering consultants before moving on to the final procedure: very possible in this case because no company has ever built such gigantic assemblies before.

Allentown Metal brought Welding Training & Testing Institute in to assist in completing the WTC Transportation Hub project. A number of quality inspections have to be performed by third-party experts, and WTTI is a qualified inspection agency, regarded as an independent agency contracted to perform certain nondestructive inspection processes. The agency is providing nondestructive testing and certified welding inspection services to supplement Allentown’s in-house quality program; when additional qualified inspectors are needed WTTI provides that service. Certain areas require 100% testing and inspection by various methods: visual, magnetic particle and ultrasonic testing methodology. Another inspection agency is performing radiography testing.

WTTI’s Bob Weissiner and other expert welding professionals from WTTI helped to set up and fine-tune temperature measurements. They applauded Allentown Metal Works’ consistent use of Tempilstik temperature-indicating devices. Allentown’s welders use the Tempilstik devices for pre- and post-heat determination as they work to stabilize the material. This provides precisely calibrated measurements for inspection and documentation purposes.

For preheating and postheating in weld areas, it is necessary to maintain temperatures in the 325°-375°F range. The material is high-strength, low-alloy 709 HPS 50W, especially resistant to weathering, and used almost exclusively in construction and bridge building.

The Estik was developed for critical temperature monitoring applications, such as checking finished welds.

Weissiner further suggested using Tempil E-stick visual calibrated measuring devices, to provide a temperature number confirming the Tempilstik’s indication to the welder. Now, the procedure is for the welders to use the Tempilstiks as they heat the metal, and for the Allentown foremen and inspectors to use calibrated Tempil E-stick instruments to check the finished welds.

When the metal being worked is above 4 in. thick it is heated to 350° F, but after welding a postheat treatment of 450° to 600° or 650° F is employed. The welder is particularly interested in seeing that he has reached the highest temperature required. Thick workpieces must cool for several days to be sure the molecular structure is in the final state so they can be X-rayed.

Allentown is also using WTTI welding engineering services to provide technical guidance on a consulting basis.

The manual temperature-indicating sticks with calibrated melting points are stroked on the workpiece like a crayon, and the mark turns liquid at any specific stick’s rated temperature. In use, the welder has one indicator stick calibrated for the lower limit and one for the higher limit of the procedure. When the crayon-like mark of the lower-rated crayon on the workpiece turns liquid, the welder knows the indicated melting point has been reached. When the mark of the higher-rated crayon turns liquid the welder knows the piece has become too hot and must be allowed to cool down a little, then tested again.

Crayon type indicators are available in metal holders in a wide range of temperatures. Two are usually employed, one for lowest permissible preheat or interpass temperature, one for highest permissible. The NRC and TVA, among many others, are confirmed temperature indicator stick users.

For more information, contact Mike Schiavone at Allentown Metal Works, Tel. 610-770-7400.