Blog

Can GCC Heat Treat Our Vessel?

Our Specialty is Vessels: Gulf Coast Combustion specializes in on-site post weld heat treatment of large pressure vessels. The codes we most often PWHT to are ASME Sec. VIII, Div. 1 and/or UCS-56. Many companies are looking for new ways to cut down on costs while maintaining a high quality of service. We strive to…
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Updated Web Experience

Welcome to our new website! GCC has updated its website to help our user's experience and increase the ease of finding relevant information. We hope that you enjoy it and take a few moments to look around and explore the new look. The primary objectives of our site development effort were focused on aesthetics, simplifying…
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8 Consumable Items on Heat Treating Job Sites and Why They Matter

8 Consumable Items You Need to Know About: Direct Gas Fire Heat Treating [caption id="attachment_645" align="alignright" width="254"] A bulkhead used to close off the end with a space for burner insertion. Made from road mesh and insulation.[/caption] Consumable items on a heat treating job site are used in the process to complete the service. A consumable by definition is a…
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100′ Vessels: PWHT By the Numbers

Heat treatment on vessel

Panoramic image of large pressure vessel after PWHT.

 

Check out the figures achieved on this 100' + vessel:

120 – length of vessel in feet
11.5 – width of vessel in feet
195,765 – weight of vessel in lbs.
4 - # of gas trains used
24,000,000 – minimum BTU’s used in equipment
280 – labor hours needed to complete in less than four days
6,000 - sq. feet of fiberglass insulation used

PWHT on any vessel takes specialized knowledge, preparation and execution to complete. But what about those big vessels over 100’ in length? They take strategic measures and planning to complete accurately and quickly.

Some tips for fabricators to prepare for heat treating 100’ + vessels:

1. Vessel growth. As a rule of thumb, vessels can grow by up to 1” per 10’ of length during the heat cycle. The longer vessels need more space in their supports to accommodate this growth.
2. Plenty of exhaust. With up to four gas trains (or more), hot air must have enough exhaust to escape so it doesn't lead to back pressure.
3. Industrial power supply. Many shops will opt to let us to use their industrial power source for equipment during heating. Each gas train requires 480V (3) phase with 30 amps start up.

On-site servicing of these vessels is the most desired way to achieve PWHT in most circumstances because of the sheer volume of vessel to be transported. The less these vessels must get on the roads, the better, resulting in less chance of damage through transportation. On-site PWHT can save thousands of dollars in heavily permitted transportation costs.

Interested in post weld heat treatment on a 100' vessel? Give us a call! (713) 425-3773.

Professional Heat Treating Consultation

Looking for industrial heat treatment consultation to help your company implement new strategies and processes? Gulf Coast Combustion’s extensive knowledge and consultation is now available across the US and globally. WHAT WE OFFER: [caption id="attachment_544" align="alignright" width="426"] GCC consultation with client over new construction to implement in-house PWHT capabilities.[/caption] • Full-service consultation on planning and building…
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Dedicated to Growth through Education

[caption id="attachment_501" align="alignright" width="367"] Brooke Benefield, second from left, with Goldman Sachs 10KSB program administrators and faculty at graduation.[/caption] Brooke Benefield, a Gulf Coast Combustion partner, has recently graduated from the Houston chapter of the Goldman Sachs 10,000 Small Businesses program in May 2016. The program is designed by Babson College, the nation’s top-ranked entrepreneurship school…
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Time-Lapse of On-site PWHT Pressure Vessel

Time-Lapse Video Check out a time-lapse of the post-weld heat treatment process on a large pressure vessel on-site at customer location. The video walks you through the initial set up, cook and strip out of PWHT on an 85' X 11' vessel. The process here is using ceramic fiberglass insulation along with high-velocity gas combustion equipment to complete PWHT in accordance…
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Drying Out Monolithic Refractories

Refractories are heat-resistant materials used for the retention of substances at high temperatures in furnaces, reactors and other processing units. In addition to being resistant to thermal stress and other elements induced by heat, refractories are usually required to withstand physical wear and corrosion by chemical agents. Monolithic (“unshaped”) refractories are used to advantage over brick…
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Practice Makes Perfect

Employee Training Gulf Coast Combustion is busy preparing for 2016 with intensive training on various forms of heat treatment. We continually ensure the high quality our clients have come to expect by keeping our technicians up-to-date and fully trained on combustion and electrical resistance heat treating best practices and safety precautions. GCC prides itself in having highly…
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The Science is in Our Name

As part of our company’s core specialty, it is important to understand the basic definition of combustion and its purpose as one of the processes in industrial heat treatment. All forms of heat treatment have the same outcome – increase the integrity/longevity of the equipment. The difference is the means to get there. Gulf Coast Combustion…
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Exploring “Gas Train” Equipment Usage

The equipment setup on gas fire jobs is usually referred to in the industry as a “Gas Train.” Our goal is to educate you on some of the inner workings of all that equipment; what it is, what it does, and why it does it. The Gas Train utilizes a mixture of dry gas and…
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Strip Chart Recording: How it’s Done Accurately

Measuring and recording the time and temperature of the heat cycle is one of the most important aspects of heat treatment. Heat treating cycles must be accurate so that the product being manufactured can fully withstand the high pressure, high temperatures and/or various materials that the product endures once it’s in use. The recording of the heat cycle is proof that heat treatment occurred at the time and temperature that conforms to the engineered specifications. Recording the time and temperature is accomplished through the use of thermocouple wire and a strip chart recorder that are interconnected to the heat treating console.

What is Thermocouple wire?

Type 'K' T/C Wire

Type 'K' T/C Wire

Thermocouple wire is a “sensor” composed of dissimilar metals used for measuring temperature of an object. It has the ability to convert heat energy into electrical energy in predictable amounts. The information is sent to a temperature control device (heat treating console) that regulates power to the heating source and documents the temperature on the recorder. Thermocouple Wire (aka: T/C) is insulated with a brown jacket and can withstand high temperature applications. GCC uses ANSI Type ‘K’ T/C wire because it provides the widest operating temperature range. Base metals of Type ‘K’ are Chromel (90% nickel and 10% chromium) Alumel (95% nickel, 2% manganese, 2% aluminium and 1% silicon.)

How are T/C's attached?

Most T/C’s are attached by means of a Low Capacitator Discharge Unit. A thermocouple attachment unit (TAU) by capacitor discharge action will affix fine thermocouple wires directly to the workpiece so that the surface of the material becomes the thermocouple junction and as a result, gives an immediate penetrative temperature. In other words, the T/C is “welded” onto the workpiece via TAU and will read the true temperature.

The number of thermocouples required for heat treatment vary widely between materials and engineering code standards. Gulf Coast Combustion's extensive knowledge of ASME code (among others) and alloy specifications form the groundwork to constructing a highly customized heat treating procedure for our clients.

What is a recorder?

Strip Chart Recorder

Strip Chart Recorder

A recorder is a heat treating instrument that uses a strip chart to record time vs. temperature. A strip chart is a continuous piece of paper that records (via printer) temperature and time for as long as a particular procedure requires. The strip chart is coupled with a chart sticker identifying all measured thermocouples and their placement and given to clients at the end of the job. A digitally recorded strip chart is a newer technology available to clients, and will be discussed in detail in a future post.

Where each thermocouple is placed measures 1 point, or zone, on the recorder. Recorders come in multiple zones – 6, 12 and 24 pt. On a 24 pt. recorder you can measure twice the amount of thermocouples as a 12 pt and 4x as much as a 6 pt. One recorder is usually sufficient to complete most jobs. More than one recorder might be used when there are two different heat treating projects at one jobsite or there is a workpiece large enough to require more than the 24 allotted zones.

Recorder Calibration

Recorders are used on every job and must be calibrated to remain accurate. Calibration is "the setting or correcting of a measuring device, usually by adjusting it to match or conform to a dependably known and constant measure." GCC’s recorders read very high temperatures in real time, without delay, to accuracies of +/- 3°F.  Over time there is a tendency for results and precision to deviate when measuring parameters like temperature. To be confident in the results being measured, there is an ongoing need to service and maintain the calibration of equipment throughout its lifetime for reliable and constant measurements.

GCC’s recorders are annually calibrated (at a minimum) by third party vendors and a calibration certificate is provided with every recording.

An accurate temperature recording is the key to flawless heat treatment. Thermocouples and recorders are used in conjunction to conform to the specifications of each and every workpiece to maintain industrial standards and safety. Click here for our Services Offered or get in touch with Gulf Coast Combustion today to discuss your heat treating needs.