Table 1A stress values for pipe 5

[heaterguy]

When we have several stress tables for similar pipe, which one do we choose?

For instance, SA-312-316 has the following:

Smls. & wld. pipe, 20,000 psi cold
Smls. & wld. pipe, 20,000 psi cold
Wld. pipe, 17,000 psi cold
Wld. pipe, 17,000 psi cold

We use these pipe for the ASME vessel to contain electric heater bundles. Our design temperatures are usually high.

For instance, SA-312-316 has the following:

Smls. & wld. pipe, 17,000 psi @ 600'F (note G5)
Smls. & wld. pipe, 12,600 psi @ 600'F
Wld. pipe, 14,500 psi @ 600'F (note G5)
Wld. pipe, 10,700 psi @ 600'F

Since this is a pipe body, would the following note apply?

Note G5: "Use of these stresses may result in dimensional changes due to permanent strain."

 

[jte]

At 600°F you are not in unusually high temperature service. These materials do not have time dependent allowable stresses until over 1000°F. However, yes, you will have permanent strain if you use the note G5 values: Take a look at Table Y-1 and you'll see that the allowable stresses are only a ksi or two below yield. Thus every place you have a structural discontinuity - shell to head, nozzles, etc. you will easily exceed yield. Whether or not that strain is acceptible will be up to the AI (at hydro) and the owner/user once the vessel is in service.

jt

 

[heaterguy]

jte,

Thank you for this information.

What does it mean to exceed yield?

Imagine a 10" pipe body vessel with a 300# body flange on one end, a weld cap on the other end and 4" inlet / outlet connections on the side of the vessel.

Also, please may you consider higher design temperatures.

Heaterguy

 

[unclesyd]

We used to call the different values High and Low.
If you look at the notes by the material you will find something like the following

You could use the higher values from 200°F to 1050°F if you could allow a little deformation. The stress values exceed 62 1/2% of the yield but not over 90% in this temperature range. This values are not to be used for pipe and flanges.

Any use of the stress values of this material above 1000°F requires that the Carbon be above 0.04%.

 

[GenB]

you the heaterman have to use the lower stress because the deformation on flange gasket,
you can use the higher stress in the end cap.
Electric heaters are often use in higher temp aplications,
you may not be right at 600F and so not complying with the Code.
er

 

[metengr]

In situations where time dependent effects (creep deformation) on properties do not occur, exceeding yield strength means that the material permanently deforms under load. There can be local yielding of material or there can be yielding of a scale that results in total distortion of the pressure retaining item. Local yielding is permitted for some materials provided you account for this behavior.

 

[ijzer]

We use the higher values for pipes, tubes and vessel walls and the lower value for flanges , because there , deformation is not allowed . It will cause leakage.

 

[heaterguy]

Everyone, thank you for your reply. It looks like we have branched to several topics. The main topic is pipe stress values.

unclesyd, please clarify. Why are there two sets of high values and two sets of low values? Do you think this application will allow for a little deformation of the pipe body?

unclesyd, please clarify. You could use the higher values from 200°F to 1050°F if you could allow a little deformation. The stress values exceed 62 1/2% of the yield but not over 90% in this temperature range. This values are not to be used for pipe and flanges.

unclesy, we agree with the 1000 deg. F temperature limitation for SA-312-316. We would use SA-312-316H above 1000 deg. F.

GenB, this topic is not about flanges.

metengr, right on! Do you think we can use the higher stress values for pipe body vessels? Again, just the pipe body, not the flanges, weld caps, etc.

ijzer, we are leaning towards this direction. Thank you for your reply.

 

[sjrfc2]

I don't have the stress tables right now but what I remember from using them before was that there were applicability columns (near tensile and yield numbers). I always wanted to use the stresses that were applicable to the Section that the vessel was constructed in accordance with. It seemed like one entry for a material stresses would be for Section I and provide a max temp and show that it was not permitted (NP) for Section III. Directly below that line of stresses the same material might be listed for Section III application with a different max temp limit (and not permitted for Section I). I'm not sure if this helps. What I came to assume/conclude was that there was something in the development of the efficiencies/stress values for the different Sections that drove them to using different values. I've tried to make sure that I'm using the stress value shown applicable to the Section column that I was working on.

 

[heaterguy]

All four of the SA-312-316 VIII-1 values are good to 1500 deg. F. However, note G12 says at temperatures above 100 deg. F, these stress values apply only when the carbon is 0.04% or higher on heat analysis. 316H grade pipe does not have the G12 limitation.

 

[GenB]

I am sorry I distracted you, look that you only want the good stuff, note that here you will always get the"marginal advise".
are you a student?

 

[jte]

heaterguy-

I think your question on exceeding yield has been well answered by unclesyd and metengr. As GenB and izjer both pointed out, you'd want to avoid the note G5 values for flange design. So... to sort out why there are four lines, focusing on notes G5, and G3 (but read the rest of them also!) and at temperatures where creep does not play a role:

Line 5: Applicable where some yield (deformation) is acceptible and where you don't have a weld joint efficiency to consider.

Line 6: Applicable where some yield is less tolerable and you don't have a weld joint efficiency to consider. eg: flanges, longitudinal tensile stress check.

Line 7: Applicable where some yield (deformation) is acceptible and where you must consider the joint efficiency of the welded pipe. Note G3 states that an E of 0.85 is included in these stress values. Not coincidentally, the allowable stresses in this line are... wait for it... 85% of the values in Line 5! You might use this line for circ stress calc's.

Line 8: Applicable where some yield (deformation) less tolerable and where you must consider the joint efficiency of the welded pipe. Again, note G3 states that an E of 0.85 is included in these stress values. Compare this with line 6. Not coincidentally, the allowable stresses in this line are... wait, wait... 85% of the values in Line 5.

So your basic decision making process will be to answer two questions for each evaluation (circ stress, long stress, etc) of each component: 1) Is some permanent deformation acceptible here? and 2) Does the calc involve the long seam and thus I need to account for the joint efficiency?

Once you've answered these two questions, your decision as to which stress value to use should be straightforward.

sjrfc Good point, but in this case all four lines are allowed up to 1500°F for VIII-1.

jt

 

[jte]

Darn copy and paste errors! Needless to say, delete the last sentence in the Line 8 paragraph above!

jt

 

[heaterguy]

Yes, my last reply also had a typo. It should by 1000 deg. F, not 100 deg. F.

 

[unclesyd]

As I understand it you are using a shell to hold a flanged bayonet heater. Is this a production heater for sale or a heater for in house use?

You can probably use 316 for your shell if you can allow the above mentioned distortion, as it will surly distort. If you can pick the pipe, get the higher carbon material. The distortion can take several forms usually the pipe will bulge and the hot nozzle centerlines will move. An additional point to consider is the 4" outlet flange as it will be at your process temperature. It should be at least Sch 80.

There are a couple of other points that need to be addressed like the process fluid, operating parameters and control scheme to stop overheating. As you are operating on the edge, the heater control scheme to prevent overheating from radiant heat and low flow are critical.

Is the process flow continuous?

 

[heaterguy]

This is a very common application. The heater bundle fits into an ASME pipe vessel. Some applications are liquid some are gas. Some have low temperature outlets some have high (1200+ deg. F). Some applications have phase change.

The ASME pipe vessel can be vertical or horizontal. Typically the vessel is as hot as the process but in some high temperature gas applications, the vessel can be hotter than the process and even approach the heater bundle temperature.

The horizontal ASME pipe vessels typically have a fixed bolt hole saddle on the inlet side and a slotted bolt hole saddle on the outlet side. This allows the ASME pipe vessel to grow in length without bulging the ASME pipe vessel.

For instance, a 10" 300# 36 element heater bundle inside of a 10" sch 80 vessel: The 36 elements are evenly distributed inside of the vessel and the flowing fluid pulls heat off of the 36 heater elements. The vessels are typically 3 feet to 14 feet long. The heater bundle also has an over temperature sensor and controller.

Typically the inlet and outlet connections are perpendicular to the ASME pipe body and do not see any of the radiation from the heater bundle.

Based on the valuable information, within this post, which stress table would you use?

Smls. & wld. pipe, 20,000 psi cold, line 17
Smls. & wld. pipe, 20,000 psi cold, line 18
Wld. pipe, 17,000 psi cold, line 19
Wld. pipe, 17,000 psi cold, line 20

Note: line numbers are from 2001 ASME Table 1A

 

[unclesyd]

Personally I would use the lower stress values, especially for welded pipe, as the end product is going to be marketed. If you push the limit and then the end user pushes your limit and there is an event it will be extremely hard to justify the use of the higher values in the design.

I just checked on our heaters (6" & 8") and we normally used the higher stress values, but this decision is tempered by our process and operating experience.

 

[GenB]

Note: line numbers are from 2001 ASME Table 1A

Are these Coded new construction vessels?

2001 Ed?