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Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. Hello everyone, We will be smart pigging the convection section of a box furnace and we need to take a tube sample weld to weld. My question is if the tubes within a furnace are considered pipe and designed to B Additional question, what are box furnaces designed to?
Thank you very much for your time in advance.
Procedure for Fired Heater Design
I've seen both Purchaser's choice in most jurisdictions as far as I'm aware. Take a look at API and though, lots of good stuff. API is usually used to determine thickness. In terms of inspection criteria, typically B Depends on the purchaser as NBrink said. According to the scope section of B If it's flame heated then should be API or similar.
Can you get a pig round all the bends? Thank you all for your responses. I will pull up B LittleInch - Yes, you are correct in that it is a fired heater.
The tubes are 6" in diameter and include deg SR U bends, but the smart pigging vendors we've reached out to can get around as low as 1D bends which is the case in this heater. Again, I appreciate all of your responses. First time posting on here after utilizing the forums nearly everyday as I begin my engineering career 5 months fresh out of college. Sure, the wall thickness is per APIbut there's not much to beyond creep rupture life API even says: "The pressure design code shall be specified or agreed by the purchaser.
Pressure components shall comply with the pressure design code and the supplemental requirements in this standard. Red Flag This Post Please let us know here why this post is inappropriate.Log In. Thank you for helping keep Eng-Tips Forums free from inappropriate posts. The Eng-Tips staff will check this out and take appropriate action. Click Here to join Eng-Tips and talk with other members!
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Join Eng-Tips Forums! Join Us! By joining you are opting in to receive e-mail. Promoting, selling, recruiting, coursework and thesis posting is forbidden.Fired Heaters
Students Click Here. Related Projects. I am doing some study on the design of direct fired oil heater for refinery used.
Normally the design basis for tube wall thickness of refinery process heaters coils, are based on API RP for Structural parts of the heater could be built according to ASME. Regards Luis.This calculator uses curve fits of the stress values and formulas from the API RP to calculate the minimum tube wall required.
Esteem Projects Pvt. The formulas and correlations presented herein are all in the public domain and are to be used only as a learning tool.
Note that any product, process, or technology in this document may be the subject of other intellectual property rights reserved by sponsors or contributors to this site. This publication is provided as is, without any warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of fitness for a particular purpose, or non-infringement.
The formulas, correlations, and methods presented herein should not be considered as being recommended by or used by the sponsors of this site. The purpose of this site is educational and the methods may or may not be suitable for actual design of equipment. Only a fired heater design engineer is qualified to decide if a calculation or procedure is correct for an application.
Need professional Fired Heater Design Services? Get in touch! Disclaimer: The formulas and correlations presented herein are all in the public domain and are to be used only as a learning tool.Active, Most Current.
API Standards for Heat Transfer Equipments
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Complete Document. Calculation of Heater-tube Thickness in Petroleum Refineries.The guidelines and procedures included herein are appropriate for a typical direct fired heater of the types found in refineries and gas plants, and is not expected to include specialty heaters or furnaces that include reaction in the tubes due to heat or catalysts. Considerations of plot area: The area available to place the new unit is one of the first items to be considered, and often leads to the determination of the heater configuration selected.
If the plot area is very small, frequently this leads the designer to select a vertical cylindrical heater design since the area required is much smaller, than an equivalent horizontal tube heater. Shipping sizes and considerations: No matter what the heater configuration or overall size of the heater, it is important to know the method that will be used and the shipping piece size that can be cleared.
For larger furnaces, it is important to always keep in mind during the design, how best to split the pieces for shipment. The reason for this is that it is normally lower cost to fabricate as much as possible in the shop while minimizing the field work to assemble final unit. Basic data needed for heater design: The minimum amount of data needed to create a heater design would be as follows:.
For the purpose of demonstrating the methods below, we will assume a heater is required to meet the following data:. Radiant Configuration Selection: For the first example, we will say that plot limitations make the Vertical Tube Cylindrical Design more attractive.
So if we were going to design this heater as a vertical tube cylindrical heater, we would need to rough out the tube circle and tube length to start with. We will start with a radiant section containing 30 tubes. Note that the API states that the average flux is normally based on a 2 nominal tube diameter spacing, but does not require this spacing.
The actual tube circle calculation is a little complicated, as we will see later, but for now we can use the approximation of no. If we use 38 tubes, then the tube circle becomes 8. Convection Section Preliminary Sizing: At this time we only need to consider the number of tubes wide and the effective length that we want initially to start the design.
The effective length can vary depending on final heat transfer calculations, but a rule of thumb for this length on a vertical cylindrical design is to start with the tube circle dimension, rounded up to an even 3 or 6 inches, in this case 8. For the number of tubes wide, you would normally start with 4, and then go more or less as may be needed during thermal design runs. The tube length and tubes wide need to take into account the convection box overhang, and space required for crossovers, radiant tube pulling doors, etc.
API requires that the shield shock tube section has 3 rows deep. The shield section always uses bare tubes. API requires the first row flux to be included in the average heat flux density of the radiant section. The remainder of the convection section tubes may be bare or with extended surface. Per APIthe convection section must be designed to allow for two future rows of tubes.Refineries and petrochemical plants form some of the major sections of the hydrocarbon industry and consume much of the fuel that is burned in furnaces heaters and specialty furnaces, such as reformers and crackers to meet process heating requirements.
Heaters consist of three major components: the steel structure, the refractory, and the tubes and pipes that carry the process fluid. The steel structure is durable and can generally remain in service for 30 yr—40 yr without any major maintenance e.
Refractory repair and replacement in heaters is part of regular maintenance checks, and generally repairs are required between turnarounds every 3 yr—4 yr. An analysis to evaluate the economy of replacement vs. The lifetime of heater tubes varies from 5 yr—15 yr, depending on the material of construction and the severity of conditions they are subjected to during heater operation.
Assess remaining life for heater tubes
The approximate cost ratios for heater tube materials—i. Process heaters are used to provide requisite heat to the feed in an enclosed box box or cylindrical. They are internally lined with refractory using single and multiple burners where fuel is fired for generating heat.
Definitive guidelines are available for most process services regarding the calculation of tube thickness and the selection of tube material of construction MOC. There has always been an inherent competition to achieve increased user acceptance for any product, and that can be achieved in two basic ways: offering the same quality service life and minimum specification requirement compliance for a lower cost, or by offering improved quality improved service life or improved specifications at the existing cost.
To extend heater tube life, improved exotic metallurgies are being evolved almost every year with higher allowable stresses for higher temperature applications. However, the development of new, exotic MOCs only will not ensure the optimized and economic utilization of any tube in service until methods for estimation for the reliable remaining tube life are in place. This estimation becomes critical for the following cases, as well:. This not only buys time until the next planned shutdown with the heater under optimum operation, but also ensures the safety of the system and personnel during heater operation by either restricting the operating parameters before the next planned shutdown, or by scheduling the next shutdown with the present heater operating parameters.
The approximate initial cost ratios for radiant tubes vs. The cost of a refinery shutdown due to a heater-dependent outage and the subsequent rebuilding may range from few days to several weeks, depending on the extent of damage. For a few cases, losses due to heater outage and rebuilding for units that are solely dependent on heater operation are also calculated to be read in the context of the Indian refinery :. Coils are critical for heater operation and, based on the above data, it is evident that a heater outage caused by general coil failure can cost significantly more that its own material cost.
The simplest way to demonstrate the impact of any event for any engineering execution is to draw the angle of impact regarding the stage phase FIG. Although the angle of impact is constant, the magnitude of impact in terms of cost and time varies significantly depending on whether the flaw is determined and corrected at design stage minimalconstruction stage significant or at post-commissioning stage catastrophic.
The guiding curve may or may not be linear in actual cases. For heater tube failure cases, due to thickness loss, the first two stages are already completed; the intent is to avoid the catastrophic impact of tube failure by determining the safe operation life with maximum integrity operating window IOW parameter limits.Heater Sim.
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