Monthly Archives: July 2014

Post Weld Heat Treating

Post Weld Heat Treatment (PWHT) is another term for relieving the stress from a material and allowing it to return to its original state. The stress relief process involves diminishing and redistributing the small folds and cracks (called stresses) in the metal that are created during the welding process.

Post Weld Heat Treatment is an essential practice in order to repair the macro structure of the welded material. The primary benefits of this process include the removal of hydrogen (which can cause cracking), increased ductile strength, and increased resistance to corrosion. The process of post weld heat treating includes relaxing and soaking the materials. While there is no universal rule for the temperature and length of time for these processes, the most commonly used formula prescribes a 1 hour soaking period at peak temperature per 1 inch (25mm) of thickness for each joint.

The stress relieving process can be performed in many different types of heat treating furnaces. The type of furnace required for post weld heat treatment can be a gas or electric furnace, the temperature ranges can vary greatly, and can be equipped with or without fans. Each of these options depends on the type of the material being heat treated, the desired outcome, and the specific process that is being performed.

The Post Welding Heat Treating process is a vital procedure for certain metals in order to maintain specific thicknesses or grades of quality. In some cases, heat treating can be detrimental to the welded metal if the procedure is not performed correctly, causing mechanism failure and corrosion. Steel is a metal that is often mishandled more than others and must be cared for properly. The tempering or aging process can cause the mechanical properties of the steel to deteriorate. Quenched and tempered steels, for instance, must be post weld heat treated at a lower temperature than the original tempering occurred at in order to preserve the natural strength and micro-structure qualities.

If you have more questions about the Post Weld Heat Treating process or PWHT Furnaces, contact us at Baker Furnace. Our on-staff industry experts are always available to assist you.

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7 Questions to Ask Before Buying a Car Bottom Furnace

Purchasing a Car Bottom Furnace is a large undertaking with many variables and expenses to consider.  We’ve compiled a few common questions that always come up as we work with our customers to build them the best quality car bottom furnace.

Here are some important questions to ask before you purchase a Car Bottom Furnace.

1. What is a typical Temperature Uniformity Specification for a Direct Fired Car Bottom Furnace?  A Car Bottom Furnace typically operates at plus or minus 25 degrees F uniformity inside the furnace’s “working space”. Tighter uniformity ( plus or minus 10 degrees F) has been achieved on some of our direct-fired units. Temperatures typically are in the 1350 degree F range.

 2. Does the Car Bottom Furnace  have pressure controlled Flue Dampers and what is the benefit?  A Car Bottom Furnace should utilize pressure transducers and a control motor/linkage that adjusts the flue. These pressure controlled flues ensure excellent furnace uniformity.

3. What temperatures can I achieve inside the Furnace?  Generally, a Car Bottom Furnace operates from 1000 degrees F up to 2200 degrees F.  High quality manufacturers should insulate the furnace with a combination of Ceramic Fiber and, Castable Refractory and Heavy Duty Refractory brick.  Linings as thick as 12” thick are used on 2200 degree F units.

4. Is the Car sealed to the side and back walls when inside the Furnace?  A Car Bottom Furnace should utilize some type of “bumper” system that thoroughly “seals” the car inside the furnace.  The drive Mechanism for the Car is located beneath the Car shielded by the Refractory surfaces.

5. Is the Control Panel approved by an accredited Agency?  Any good manufacturer will be accredited by the U.L. The U.L. is an independent, global accredited safety science company aimed at maintaining s high standard of safety in the workplace and quality of the product being manufactured. Control Panels have a U.L. Classified Sticker affixed inside. All components in the U.L. Classified Control Panel are U.L. listed or recognized.

6. Is the Combustion System rated to meet Factory Mutual, IRI and NFPA 86?  A Car Bottom Furnace should include numerous safety components including redundant Gas safety shut off valves, Isolation gas cocks, High/Low Gas Pressure Switches, Air Proving switches and flame supervision with Ultra Violet (U.V.) Scanners.  Burners should not light until a purge air cycle has been completed at start up. The burners light on low fire and modulate safely to high fire via linkage and drive component.

7. Can I receive Installation/Start up assistance with my order for a Car Bottom Furnace?  A standard Car Bottom Furnace should be supplied with detailed general arrangement drawings as well as track installation drawings.  Baker Furnace has engineers on staff who assist on site with the installation and start up of your furnace.

 Car Bottom Furnace

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Depending on your requirements, there are several other questions that may come up, but we hope this helps you in your initial stages.  If you need more information, check out our Car Bottom Furnace presentation here:  BAKER FURNACE CAR BOTTOM FURNACE LINK

Composite Materials 101

One of man’s greatest and most beneficial inventions is the composite material. We use these materials every day and most of the time we don’t even know that we are using composite materials. From pens to car parts and even the components making up your computer monitor, almost every modern convenience is made of a composite material.

A composite material is any material that is made of two or more different materials each with different properties. The purpose for creating these materials is to increase the strength of the item as well as its durability. Some of the most basic and ancient composite materials, such as bricks, are ones that we still use today. We can trace the existence of bricks back to the time of the Ancient Egyptians. These straw and mud composite bricks are the primary material that the famous pyramids were built out of.

There are also some naturally occurring composite materials. Palm and bamboo tree wood have been used in both prehistoric and modern construction. These woods are known for being exceptionally strong and continue to be the principal material used in scaffolding, fabric manufacturing, agriculture, and building. Bamboo was even used to make an assortment weapons including blowguns, bows and arrows, and Samurai swords.
While some composite materials can be handmade, the majority of products composite materials must be processed. One of the most popular composite materials used in manufacturing is carbon fiber. Carbon fiber is created by being heated and compressed in an industrial oven. The range of products that benefit from carbon fiber is impressive. This composite material offers manufacturers high tensile strength, high temperature tolerance, high stiffness, high chemical resistance, a low thermal expansion and carbon fiber does all of this while being very light weight. A variety of industries from aerospace and automotive to wind energy utilize carbon fiber. Carbon fiber can be used to replace a multitude of heavy car parts, enough to lighten vehicles up to 60%. A car that is 60% lighter would use 30% less fuel, emit up to 20% less pollution, and leave more cash in the pocket of car owners. The current cost of carbon fiber is the only thing holding back this new manufacturing trend.

Currently the U.S. manufactures more than 36% of the world’s composite materials, and the demand continues to grow. Worldwide, the composite market is worth $106.7 billion. With increasing demand each year, and new applications always being discovered, these amazing composite materials are on the forefront of technological advancement.

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