kuldeep76 said:
Should I calculate the pipe wall thk for each condition as per ASME B31.3. Or is there a shorter way?
Code requirement is defined in 301.2.1(c):
When more than one set of pressure–temperature
conditions exist for a piping system, the conditions
governing the rating of components conforming to
listed standards may differ from the conditions governing
the rating of components designed in accordance with
para. 304.
Short; without proper assessment of all individual combinations, you cant really tell which one is the prevailing combination and thus your design condition.
Huub
- You never get what you expect, you only get what you inspect.
Hi XL83NL, I agree with you. I had come across a PT calculation excel sheet at my workplace.
In there we can assign any random thk to the entire size range of CS pipes falling in the project
Say...
1/2" to 1 1/2" 80SCH
2" to 8" 40SCH
10" to 24" 20sch
above 24" as per line operating conditions
This sheet, strips off the Mill tol and Corrosion allowance from the pipe wall thk.
This wall thk is used in the MAWP formula (as per ASME B31.3) to verify by back calculation if the value thus found, exceeds the rating MAWP as per ASME B16.5
All we have to do is keep reducing the pipe schdules to the point of tip over. IE. the calculated MAWP gets lesser than the flange rated MAWP, which means we have reached the failure point. So we go the the next higher thk and finalise the design. What's your call on this kind of working?
However if the calculation is to be done the usual way by calc the thk and then chking against the MAWP then is would be cumbersome.
Not sure how would it look like. So ...my question if there is a way to point out the worst case !!!
But yes I would be certainly more comfortable to check all the design conditions the line would have to face before passing it.
Thanks all for your help
Hi LittleInch
You said-So what's the point of specifying the design pressure if you're not going to use it??
Are you assuming that Thk calc here, is being considered without the design parameters?
As per the method we start with a random wall thk and go on reducing it. This is done till the Calced MAWP is just above the flange rated MAWP. The MAWP thus calculated has the allowable stress component which is in proportion to the design temp. The value hence obtained must be greater than the MAWP as per 16.5. This mawp also is in proportion with temperature.
So the design pressure and temperature is factored in for calc of thk. Wouldn't you agree?
You also said - Highest pressure at highest temp.
Kindly look again at the line list. For highest pressure the temperature is lower and for the highest temp conditions the pressure is lower. No single condition that fits all.
Hence I find going tru all the service conditions is the best bet in making the system fool proof as suggested by another member of this forum. Pls correct me if I'm wrong
kuldeep,
You don't seem to be understanding what I'm saying so no I don't agree with this backwards method you're proposing.
Normal method is chose a design pressure to use at a certain temperature then work out the thickness and choose the next standard wall thickness in ASME B 36.10. Simple.
The issue is what pressure do you choose to use.
You list a set of "Design Pressures", but then seme to ignore it in place of the MAWP able to be used according to ASME B16.5 flange rating. This number is available from the design temperature being used.
So no need for this trial and error system.
Your OP started by asking which ones to choose. I admit I didn't see the 195@ 176, which should be one to look at.
Is this is the same pipe but subject to different conditions or you just want to buy one thickness of pipe which covers all situations?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Only if you have a lot of money.
Why buy pipe thicker than you need to?
Now tbf, there is value in only having say three or four thickness of pipe to avoid too many and lengths make a difference as well.
If the high pressure high temp stuff is only 30m,but you have m of lower pressure stuff, why buy all that thick pipe when the majority you need is thinner??
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I guess what you want to draw from the Line List is the 'Piping Class', where pipings are grouped by service and P/T range
Yes GD2
The line list I posted at the start of the thread is for the service categorised as "D category" fluids. These have the PT range suitable for 150# class. I've just posted the entries filtered out for size 10" pipes alone (for being concise). The entire sheet has sizes varying from 1/2" to 24". So there are numerous combination of P vs T for just this one class.
If I must find the max thickness out of all these conditions then I shd get busy arranging all the temperature values on the excel sheet and feeding the interpolated allowable stresses from 31.3 & interpolated MAWP from 16.5 against each temperature entry. That's how I get the max thk in some entry that gets calculated.
In a template provided for this activity, I see a design condition picked randomly out of the bunch of PT combinations of a certain service and considered as the worst condition. Based on this chosen condition the all pipe size thks are calculated. Dunno how they arrived at this condition?? For trial, I tried using other combinations of PT to see if I get thicker values, but alas it is calculated to be thinner. There is a way to zero in on the worst PT condition, without going all the above process, which seems to elude me.
Now I've to develop spread sheet (@ 25 or above) based on the brut force method OR hitting the hammer once at the right place to get the entire ship's engine to roar back to life.
Any help on this would be very useful.
Only if you have a lot of money. Why buy pipe thicker than you need to?
Yes LittleInch
Your ans is justifiable. Nobody would buy higher thks unnecessarily. But there is another aspect where you need to keep the inventry as trimmed as possible else that are lot more challenges in store.
A pipe class is defined which included various services. Some services OR PT combinations do not require the selected pipe thk yet we add them into one pipe class so that the variety of pipes are in control.
Now 150# & 300# pipe classes contains max of the pipes. If they are to be broken down PT wise then we would end up with 20 separate thk sets(or more). The probability of mix-up happening at the site during construction greatly increases. So for that reason we generalise and keep a few services within one Pipe spec or pipe class (which may be over designed for some services and PT combinations).
This is what I could come up with my limited knowledge & experience. Pls correct me if I'm wrong.
Choosing the right materials is crucial for ensuring durability and performance when constructing piping systems. Carbon steel butt weld pipe fittings are a popular choice due to their strength, flexibility, and resistance to high pressures. However, with so many manufacturers and types of carbon steel pipe fittings available, how can you choose the right one for your project? Here are some factors that should be taken into consideration
SHOUJIA are exported all over the world and different industries with quality first. Our belief is to provide our customers with more and better high value-added products. Let's create a better future together.
Understand Your Project Requirements
Before diving into the selection process, it’s essential to assess the specific requirements of your project. Consider the following aspects:
- Operating Temperature: What temperatures will the piping system be exposed to? Different grades of carbon steel can withstand varying temperature ranges.
- Pressure Ratings: Determine the pressure requirements for your system. Butt weld pipes are rated for different pressure levels, so ensure you choose fittings that can handle your project’s demands.
Choose the Right Grade of Carbon Steel
Carbon steel comes in various grades, each with unique properties. The most commonly used grades for butt weld pipes are:
- ASTM A106: It is suited for high-temperature applications and has reasonable weldability.
- ASTM A53: It is suitable for low-pressure applications and widely used in construction.
Choose an acceptable grade according to the project’s needs and complies with the industry standard.
Consider the Size and Dimensions
Another important factor is the size of the carbon steel pipe fittings. Butt weld pipes are available in different sizes of diameter and thickness. Select dimensions that are suitable for your system’s layout and will enable the right flow rates. Bear in mind that, for high production rates, larger diameters may be required.
If you want to learn more, please visit our website Carbon Steel Pipe.
Welding Method and Compatibility
When using carbon steel butt weld pipe fittings, the welding method can significantly affect the overall performance. Common welding methods include:
- TIG (Tungsten Inert Gas): Provides high-quality, precise welds.
- MIG (Metal Inert Gas): Suitable for faster production with good penetration.
Ensure that your fittings are compatible with your preferred welding method to achieve optimal results.
Check for Certifications and Standards
Always verify that the carbon steel pipe fittings meet industry standards and certifications. Look for markings that indicate compliance with specifications like ASME, ASTM, or API. This ensures that you buy quality products suitable for your application in the market.
Evaluate Supplier Reputation
Finally, consider your supplier’s reputation. Choose a supplier known for high-quality carbon steel pipe fittings and excellent customer service. Reading reviews and asking for recommendations can help you find a reliable source.
Conclusion
Selecting the appropriate carbon steel butt weld pipe fittings for your project should not be a difficult task. This paper has shown how to make informed decisions by identifying your project requirements, choosing the correct grade, and thinking about the size welding methods and quality certifications in order to achieve a successful piping system. It is also important to pay attention to quality and compatibility to get the best results for the installation and avoid future problems.
Are you interested in learning more about Metal Stamping Service? Contact us today to secure an expert consultation!