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SHELL FINAL THICKNESS
4

SHELL FINAL THICKNESS

SHELL FINAL THICKNESS

(OP)
Good day, Engineers!

For example, I already designed the tank with 1 foot method and Annex V at API 650. The thickness are 12mm, 10mm, 8mm, and 8mm. The tank has roof frame without column and has agitator at the center. Is there any other computation for additional thickness for shell plates or to check if the shell plates can carry the vertical loads like roof frame without column, and an agitator at the center.

Thank you, Engineers! God bless.

RE: SHELL FINAL THICKNESS


Appendix V is for the tanks external pressure (vacuum) loading between 0.25 kPa to 6.9 kPa . How did you decide the vacuum pressure? specified by the Purchaser ?

What about the shell stiffeners ?

You may look at the worked example at appendix V 10 .

How did you design the roof for the supported agitator?

If you provide the operation weight, frequency, and torque of the agitator with a descriptive sketch you may get better responds.

RE: SHELL FINAL THICKNESS

Lord Ets ... HTURTAK makes good sense ..

Is this the first tank you have ever designed ?

Are you an engineer or someone that just substitutes in numbers in equations .... What is your background ?

Where is your calculation for an agitator of unknown weight ?.... Agitators are designed based on a STIFFNESS not a stress criteria

What about the effects of wind and earthquake loadings on the shell thickness ?

.... or will you come running to this forum five minutes from now to ask about this ....

Show ALL of your work, assumptions, design criteria etc ..... not a half-assed preliminary result

MJCronin
Sr. Process Engineer

RE: SHELL FINAL THICKNESS

The OP is too busy and hardly ever responds or , to read the posts..

Dear LORD ets, we are waiting with sanguine hope that you will raise new questions.. we are always online and waiting to jump with a respond to your new questions since being retired engineer, we have a lot of free time ...

RE: SHELL FINAL THICKNESS

(OP)
I'm very thankful for your response Sir HTURKAK and Sir MJCronin.

The purchaser did not specify the external pressure. Simple drawing with dimensions only. I ask my boss for external pressure but he don't know. I just choose 6.9kPa. I'm sorry to say this but my intention is to over design the tank.

Over design for my safety.

I'm really sorry Sir, but structural design is my contract to them. Designing large tanks is so awesome but since I don't have any experience on it even in my college days, I'm hoping they will teach me or advice me how to design it.

I always ask my boss with few things with tanks but his response is always he don't know. And also, sometimes no soil data. Our last conversion is all about the soil test, but he has no plan to take soil test.

In my first months in my job is ok, I design steel structure. He just ask me to design the thickness of tank (just thickness). Until he told me to design the whole tank.

I used to design the tank/s with Annex V to credit the wind load and external pressure. To add stiffener and to increase the thickness of the tank. With 1 foot method and Annex V, I'm confident with my design with those reference. But I'm still thinking if I need to add or check if the shell plate thickness can carry the roof framing and agitator.

Givens in drawing
Dimesions
Design height
Operational height
Rafters
Sloped bottom
Roof slope

Givens in the table
Specific gravity of content
Design volume
Operational volume
Design pressure full of water
Design temperature
Operating temperature

Agitator weight 5tons

I compute the rafters spacing using API 650 5.10.4.4. And I use STAAD to design it, since my boss told me to use software. But I check it manually.

RE: SHELL FINAL THICKNESS

(OP)
Sir, the agitator weight is 5 tons. The torque, etc. is unknown.

RE: SHELL FINAL THICKNESS

(OP)
Yes I used Annex V.10 as reference, Sir HTURKAK.

RE: SHELL FINAL THICKNESS

(OP)
Sir MJCronin, I'm a civil engineer. With less than 1yr experience. My specialty is analysis and design of steel frame, concrete frame, etc. but not for tanks. Tanks are special structure. I'm struggling because I don't have senior to ask. In our department, we have electrical and mechanical engineer, architect, and draftman. My boss is civil engineer, but he don't know have any idea how to design any structure. That's why I need to study with myself, but not all of answers for my questions can be found at API 650. Like, is there any other calculations to increase/check the thickness of tank shell since there is roof framing and additional dead load of 5tons due to agitator.

Sir HTURKAK, your right about torque of agitator. The client should be provide that? Base on API 650 Annex L, there's alot of data to be consider and should be provided by the purchaser. I think they give us incomplete data.

RE: SHELL FINAL THICKNESS

(OP)
Based on your replies Sir HTURKAK and Sir MJCronin. There's alot be consider when designing of tank. Yes, I agree. To be honest, my boss give me an old design of tank. It is already operating since 2008. The design is very simple. The pass designer used 1 foot method only, and that's it. A very very low budget design. For example the calculated thickness is 7mm point something, he rounded up to 8mm. That's it, a less than 1mm allowance. He didn't compute the spacing of rafters. He use minimum thickness of 5mm for roof plates. Channel section for rafters without calculation, he just used an old reference book with tables of minimum sections and numbers of rafters. Minimum for bottom plates, 6mm + 3mm (corrsion allowance). Minimum top stiffener. Above all he assume the allowable soil bearing capacity of 96MPa. The old tank dimesions are dia 12.57m and 7.8m height.

I didn't used his design as reference. Because I just want to compute the values, I just don't want to rely on minimum without calculations.

I hope you can give me some advice how to design it correctly. Thank you so much. God bless.

RE: SHELL FINAL THICKNESS



Lord Ets (Civil/Environmental); if you do not provide necessary info, the responds which you will get will only be guessing..

If you want helpful responds; provide some data ( dimensions, material ,properties of the content , wind , seismicity, temperature, design pressure, agitator loads...)

In past , having worked for phosphoric acid ( reactors and storage ) tanks, there are two possible supporting systems for roof type center-mounted tank agitators,

i = agitators mounted on two beams ( for open roof tanks or flat roof tanks ) running parallel to diameter of the tank,

ii = agitators mounted on reinforced nozzle for cone roof (or dished roof for small tanks )

For your case, with cone roof, the radial rafters shall be designed to support the roof loads and the loads that will be supplied by the agitator vendor...

Your replies imply , it is better for you to ask consultancy of an experienced engineer to get safe, economical design...

Good luck..

RE: SHELL FINAL THICKNESS

My suggestion is to use API 650 for the tank, include 1 ro 2 mm for corrosion allowance based on the product's corrosivity to steel, include open vents sized using API 2000 then ignore extrenal pressure (vacuum), include wind and seismic for the tank buckling, overturning and compression, use local ice and snow loads for the roof but include no equipment loads, assume soil capacity equal to the full height liquid load (product or water whichever is greater). Use API minumum roof plate thickness and rafter quantity, basic structural analysis for the roof support structure. For the agitator include horizontal beams that span the tank to support the agitator, assume a torque based on the motor used, run vertical beams down the outside of the tank down to 300mm below the first round seam encountered. For vertical loads on the shell from rafters and the agitator, you'll find that the tank shell is quite strong but check using FEA, Roark's or anchor bolt chair type analysis. Also search this site for previous questions that include the key words agitator and tank.

RE: SHELL FINAL THICKNESS

IFRs gives good advice .... but this tank should be designed by a third-party consultant with experience .... The Consultant cost is relatively small part of the total design and installation cost and, more importantly IT IS A SHIFT OF CURRENT AND FUTURE REPONSIBILITY TO AN EXPERIENCED THIRD PARTY !

The environmental cost of a massive liquid spill in terms of possible lives lost and environmental damage pales when the services of an experienced tank designer are considered.

You claim to be a civil engineer (concrete)but are doing the best you can "learning on the fly".... Let us ask you, would you enter and occupy a multi level concrete building with NO REBAR designed by a geologist that was " learning on the fly" ????

Your sleazebag boss practices "MBA thinking" (Anyone can do any job in any amount of time") and is someone that will never take any responsibility for anything...

Always remember, a boss like yours have will take ZERO RESPONSIBLITY if there is any accident or design failure ..... He will always point to you as the tank designer, experienced or not. .... Remember, this tank could fail YEARS from now for reasons we have not even yet considered and the authorities could come looking for you !!!

Does your company require the PE stamping or sealing of documents ?.... Will you be the one certifying the tank design and safety ?

Here in the USA , we are trying to get a similar irresponsible MBA reptile out of the White House right now ....... He has caused death and destruction of many institutions and environmental programs, yet he take responsibility for anything ..... He is borderline delusional and belongs in a place where he can no longer harm others

In what country are you located ? ...... What is the liquid stored ????

MJCronin
Sr. Process Engineer

RE: SHELL FINAL THICKNESS

(OP)
Mr. MJCronin, concrete and steel frame. How about you, are you going to do that? Because I won't. If you don't know something just study and get some advice with person/s have experience on it. I thought anyone can ask some professionals here?

I'm just asking some advice, I'm not asking you to design it for me. That's learning on fly you are talking about.

I am willing to learn and to be trained. But who will train me in our company? Nothing, I'm lucking of support. To be honest, a small idea coming from my colleagues is very helpful. But also, they don't have idea.

Yes, you're right. The problem here is my boss. He already know that I don't have any idea how to design tanks.

At first, he gave me an excel file with formula of 1 foot method. Oh god it's very easy. That's why he thought this is a very easy job.

Again, our pass designer always design a tank with 1 foot method only and he didn't consider anything. He get some minimum values of tank parts. And thats it.
I don't have trust with his designs. That's why I'm here to ask you because I trusted you guys.

Tank design is not on my contract. We have mechanical engineers in our office and wondering why I'm the one who design it. I think mechanical engineers has more idea to design it.

Before. My company has two designer, mechanical and civil. The mechanical engineer only used 1 foot method. Base on his designs, he always added 5mm to his computed thickness (let say 7mm with corrosion allowance, +5mm. His final thickness is 12mm) thats it, no other computation. And his report is summary only.

I already told how the civil engineer design tanks.

Again the boss is the problem here. He is like a child as what like told me by my colleagues.

Mr. HTURKAK is right about his advice on my other thread. "If you don't like where you are, move. You are not a tree."

But again, we are facing pandemic right now. I need money to support my family that's why I accepted the work he gave. And since pandemic, it's very difficult to apply to other company. That's why I'm enduring these circumstances.

RE: SHELL FINAL THICKNESS

I feel your anxiety on lack of support from your office, but you are not alone, as there are many locations like that. You are lucky to have that many information (as you have provided) and a previous design example to follow, or compare. Relax, start review the relevant code, and do the best you are aware/capable of. The additional information will be dripping in, as the design progress forward. Industry design is usually done through iterations/cycles, as many information are not known before hand. And lastly, for the know nothing boss, unfortunately he's the one ultimately to sign off your design, and be responsible for it. I don't think he will say "I don't know" to his boss then.

RE: SHELL FINAL THICKNESS

(OP)
I'm waiting until the pandemic is gone, and look for another company.

I'm aware that these should be design with someone with experience.

Again, maybe this is so rude but I don't have a choice. My intention is to over design and over price the tank/s.
Over design for my safety and over price to make sure that these tanks construction will not be awarded to my boss.

Yes, it is so rude. But he don't care about me, he don't care about my professional license. Then we're the same.

My colleagues also complaining about his mindset. By the way, he is not the ceo/president of our company. He is just trained to be the next ceo because his uncle (the ceo) is already old.

Even if my intention is to over design and over price the tank/s, I'm still wanted to be learn how to design it.

Even if it is over design/price. There's still computations, I can show or send to my boss. By the way, I'm work from home right now. The another goal is to have reports to sent to my boss.

For example I designed it with API 650 Annex V even if there's vent. So this is over design. It is ok for me, my boss don't have idea with that.

But still I want to learn how to design it properly. I'm interested.

I only know about 1foot method, variable point method, bottom, roof, rafter spacing, Annex A, B, E, K, S, V of API 650.

That's why I'm here to ask some advice.

Thank you.

RE: SHELL FINAL THICKNESS

(OP)
Yes Sir r13, thank you. I'm trying my best, that's why I'm here to gather some informations.

All of you, thank so much.

RE: SHELL FINAL THICKNESS

(OP)
Sir IFRs, yes. I will add vertical beam outside the tank shell.

That's the problem, no info for agitator motor to be use.

For example, I already know the agitator torque. Is there any other formula to be consider. Or a fomula with relation between tank/shell and the agitator torque?

If mild steel, I always used 3mm corossion allowance.

If stainless steel what is the good value for corrosion allowance? Because I used 3mm also for my safety.

Finite element analysis. Ok ok, I get it.

Thank you.

RE: SHELL FINAL THICKNESS

You are in a tough spot, as is your customer who buys the tank, and the public that lives nearby. Fortunately, tanks are not too complicated. From what I have read, you are OK with the basic tank design using much of API 650, perhaps understand the theory behind their cookbook equations and methods such that you can derive the API equations and understand where the constants come from; and might have read other background and footnoted sources. It seems like you are now looking at the agitator. For the agitator you know the weight and torque. You can therefore design the bridge beams, I would keep them around a meter apart, include corrosion allowancees. Include all loads - wind, seismic, personnel, etc. Don't forget the connections, welds, bolts, etc. The verticals you can design for the same loads, the same way. Their impact on the tank depends on how they are attached. I would start with assuming they are welded to the upper portion of the tank and the lower ends of the verticals using 300mm square doubler plates equal to the shell plate thicknesses. this will simplify the analysis of the vertical beams. Avoid shell seams if possible. I think you'll find that the additional loads they put in to the shell plates can be determined using basic structural analysis methods, possibly confirmed with FEA. Combine load using appropriate load combination factors and look for areas of maximum stress. Stay conservative and continue to look for experts that can review your work.

RE: SHELL FINAL THICKNESS

(OP)


This is 1 example of the tank, stainless steel. As you can see, no vent.

The agitator weight is 5tons.

Sir HTURKAK, these are the datas you are looking for.

RE: SHELL FINAL THICKNESS

You may have overturning issues from seismic for a tank taller than wide and a huge weight on top. Shell anchors may be needed.

RE: SHELL FINAL THICKNESS

(OP)


And this has vent. Agitator weight is 5tons also.

RE: SHELL FINAL THICKNESS

(OP)


This is a rafters for dome. But this is for reference only. I'm design for cone roof.

As you can see, there vertical I section outside the tank shell.

I already design roof framing for steel tank and it is locate inside the tank.

But now, it is stainless steel tank. The client wants the roof framing is outside the roof shell.

RE: SHELL FINAL THICKNESS

I'd also worry about sliding down the slope.

RE: SHELL FINAL THICKNESS

(OP)
My boss told me that it should be anchored. Maybe because it has slopped bottom.

Now you can see. API 650 doesn't have section or provision about agitator and slopped bottom.

Any ideas and suggestions are really appreciated.

Thank you.

RE: SHELL FINAL THICKNESS

Bottoms uniformly sloped to one side, sometimes known as shovel bottoms are not that uncommon, but as you note, API 650 is silent on that configuration. For some slight guidenace regarding friction, see sections 5.3.1.2, 5.11.4, E.6.2.1.2, E.7.6 where friction is mentioned.

RE: SHELL FINAL THICKNESS

(OP)
Thank you Sir IFRs, what about roof framing? How do you design roof framing like that?

In my case, I used STAAD.Pro and check it manually. My boss always suggest that if the structure can be designed using software, then use software.

RE: SHELL FINAL THICKNESS

Lord Ets ;

Pls find below my notes,

i= For the tank without vent ; the internal pressure ( vacuum ) shall be calculated acc. to piping arrangement and valves ..The absence of vent does not mean the vacuum pressure 6.9 kPa will develop.. The probable vacuum pressure shall be calculated considering the emptying and filling ..

ii= The sloped bottom ; the sliding shall be checked together with applicable seismic and wind loading.. and FS suggested in the code shall be provided.If necessary, provide anchorage for sliding and overturning.

iii= The radial rafters seems to be above the roof plate.. API does not address the use of supporting system above the roof plates..

iv= You are expected to comply roof to shell joint ( compression ring ) requirements for self supported dome or cone roofs..The horizontal and vertical force flow from radial rafters to compression ring and to the shell shall be justified..

v= data provided on the dwg does not give info. for the wind, seismicity, type of content..

Good luck..

RE: SHELL FINAL THICKNESS

(OP)
Sir HTURKAK

i. The calculation of internal pressure you are talking about is can be found at API 650 Annex F? If not, can you give me reference.

Using external pressure of 6.9kPa (maximum for API 650 - Annex V) is ok or I'm safe with that? Since I can't find the section or annex in API 650 that discuss it.

ii. What section in API 650 I can use? Or what reference code? I only used API 650 Annex E for seismic design, and Annex V to account wind loads.
Can you give me some reference code to use? I really appreciate it Sir.

iii. Yes Sir.

iv. What reference code or section/annex in API 650 should I use Sir?

v. I get the value for wind velocity based on our code.

V = 290 kph
W = 1.48(V/190)^2 (Annex V)
W = 3.45 kPa

I only used Annex E for seismicity

Tank content, my boss told me to use water.
Specific gravity = 1.0


Thank you for your response Sir.

RE: SHELL FINAL THICKNESS

Internal and external pressures are not calculated during the tank design - they are usually given to you. It's like Gravity, atmospheric pressure, soil bearing capacty, solar heat input, insulation R-value, snow load or seismic parameters - they are things dictated to you from the environment, the customer, the process, the location, materials, etc. Choosing an arbitrary external pressure (vacuum) in the absence of a real load condition will make your tank stronger, but for no defined or required purpose other than an added safety factor for resisting that particular imaginary load condition.

Also, Annex V is not for wind loads. It is for internal vacuum represented as external pressure. Other sections of the basic standard cover wind buckling and overturning.

RE: SHELL FINAL THICKNESS

(OP)
Sir HTURKAK

Can you check again the 2nd photo I sent. That I.H 18B, is that a vent Sir?

RE: SHELL FINAL THICKNESS

(OP)
Sir lFRs

Therefore, I should told this to my boss? The he need to contact/email the client and request for the values specially for (internal pressure, external pressure, and seismic parametets).

I already know the location. That is why I calculate the wind load and some seismic paramters.

It means, my safety is not guaranteed if I used 6.9kPa as external pressure? Maybe this tank has large value for external pressure?

I thought Annex V includes wind load, since it has formula for total design external pressure (Ps), the greater of (Pe or W + 0.4Pe). Now I know, thanks for the information.

All of you, thank you.

Can you give me what section/annex I can read the wind buckling and over turning.

or Sir, can you give me the references/section/annex I should read to design this tank.

Thank you so much Sir.

RE: SHELL FINAL THICKNESS

See API 650 5.2 for all loads including wind and 5.2.2 for load combination factors, see 5.9 for wind girders to resist buckling and 5.11 for resistance to overturning. Actually, you can do as I did and use the search function in your PDF reader...

RE: SHELL FINAL THICKNESS

(OP)
Sir lFRs

I didn't used section 5.9 for wind girders. When I noticed that Annex V has more detailed about buckling, specially it has detailed example calculation.

I should design the tank/s for both section 5.9 and Annex V?

RE: SHELL FINAL THICKNESS

(OP)
What about the operational and design pressure of full of water. How can I use that?

When I calculate the shell thickness, I only used the formula and the height from the top of tank shell. For example in 2nd photo, I calculate the 1st or bottom course with a height of 17.00m.

And for the atmospheric pressure Sir, when or where I should use that?

RE: SHELL FINAL THICKNESS

2
I apologize for the following. I mean no disrespect to you, your boss or the situation you find yourself in. I'd love to help but this seems like a deep hole and for me it's time to stop digging.

After this, I'm done. You are going down a path to disaster, possibly putting the public in danger and causing professional ruin for you and your boss. Stop. Right. Now. You owe it to yourself, your boss, your customer and the public, not to mention the bad name engineering might suffer for your efforts.

You are taking a very simple tank design standard, making it complicated and starting from the beginning of Chapter 1 it seem y ou are not understanding why it is used or how it is applied.

Design for the actual operating conditions. Don't just throw numbers and wild guesses at it unless this is just some game your boss is playing and there is zero risk of it being built.

Annex V is for tanks with internal vacuum and that is all. It is to be applied in addition to the basic standard if and only if your tank meets the scope of Annex V. This is or should be very clear in the scope of each Annex. From what I can tell, you don't know if your tank will experience internal vacuum.

For some reason you decided to include a completely arbitrary internal vacuum in your design. For some other reason you decied not to apply Annex M for high temperature, or S for stainless or F for internal pressure etc. Why not apply them all with wild guesses at the criteria and mash it all together for a cool science project?

Choosing a completely arbitrary vacuum, temperature, pressure or any other design criteria is not what engineers do. It could be too high (increasing cost for no purpose) or too low (unsafe and subject to failure). You need to find out what the design parameters are from the purchaser. It is not up to you or your boss to decide the operating temperature, design specific gravity, corrosion alowance, product stored, corrosivity, flash point, etc etc unless those criterria are obvious by inspection. If you want to throw numbers at it, just make the whole tank 25mm thick duplex SS, stop wasting your time and it might still fail.

There is an entire annex devoted to design data to be supplied by the purchaser. Get it filled out. If no one will tell you the truth and you need to make assumptions, have good reasons for them and then write it all down including how and why you chose each one in a very explicit letter to your boss explaining why the tank design is stupid, dangerous, costly and generally useless.

If it is a water storage tank in Spain, you can get basically figure it out. But if it is at a chemical plant you probably don't have a chance in the world of guessing right. And guessing is not your job.

If the tank could be full of water, use that as a design condition. It already is if you are following API 650. Since you asked this question, we can see that you have not read or understood API 650.

Calculating the shell thickness is very straight forward and clearly outlined in API 650. You appear to be unsure of how to use the 1-foot method. Since you asked this question, we can see that you have not read or understood this part of the standard.

Atmospheric pressure is not a load to be considered unless the tank is completely sealed and purchaser is going to pull a vacuum inside. Which is one of those design conditions the purchaser needs to tell you.

Again I mean no disrespect and have probably gone way over the line here. My apologies and I hope you can get all the design criteria, find someone who knows API 650 and can show you how relatively simple it actually is for what it does, and then help you recognize the things you need that are not covered in the standard and can help you with them.

I will probably continue to foloow this thread but will only get back involved if it seems like you are going in a good direction and just need a little push here or there.

Goodbye and good luck.


RE: SHELL FINAL THICKNESS

Dear Lord Ets ;

I will try to answer to your questions which are explicitly mentioning my name and I hope my respond will not encourage you to attempt to design of the subject tanks. Your previous thread was for tank foundation design and that could be acceptable with background of a one year of structural engineering experience . However, the tank design is totally different subject and not only finding the shell thickness with simple hydrostatic hoop force such as in one-foot method. I am still at the same point that you shall ask the guidance of an experienced engineer or better perform all the tank design ..

Quote (i. The calculation of internal pressure you are talking about is can be found at API 650 Annex F? If not, can you give me reference.
Using external pressure of 6.9kPa (maximum for API 650 - Annex V) is ok or I'm safe with that? Since I can't find the section or annex in API 650 that discuss it.)


Pls read the scope of annex V ; (appendix provides minimum requirements that may be specified by the Purchaser for tanks that are designed to operate with external pressure (vacuum) loading as a normal operating condition. This appendix is intended to apply to tanks for which the normal operating external pressure exceeds 0.25 kPa (0.036 lbf/in.2) but does not exceed 6.9 kPa (1.0 lbf/in.2).
The tank data sheet ( which also the basic design data should be included ) normally provided by the purchaser. In the absence of some data ,the first step is, qualifying the absent data with some calculations and assumptions , and asking the approval of the purchaser. If the internal (in this case vacuum ) pressure is absent, if you know the process and piping ( filling and emptying rates, PV valves,..) the vacuum pressure which may develop could be estimated by an experienced engineer. In this case , the proposed vacuum pressure shall be dictated with a suitable breathing valve (PV valve)..


Quote (ii. What section in API 650 I can use? Or what reference code? I only used API 650 Annex E for seismic design, and Annex V to account wind loads.
Can you give me some reference code to use? I really appreciate it Sir.)


The sliding and OT check is required as per app. E.7.6 and 5.11 . Regarding the tank with sloped bottom, the slope will have negative impact for sliding..

Quote (iv. What reference code or section/annex in API 650 should I use Sir?)

The compression ring req. is stated at 5.10.5.2 for self supporting cone roofs. Although external radial rafters provided, the roof still self supported ..moreover, the radial rafters more complicate the tension ring required.

Quote (v. I get the value for wind velocity based on our code.V = 290 kph ....Tank content, my boss told me to use water.
Specific gravity = 1.0 )


Wind velocity 290 kph is too high...could be syclonic region ? You are attempting to design the the tank and still you do know the content ?

Quote (Sir HTURKAK

Can you check again the 2nd photo I sent. That I.H 18B, is that a vent Sir?)


Apparently there is a roof nozzle and could not be interpreted as a roof vent.

Good luck..



RE: SHELL FINAL THICKNESS



I read in detail the last post of IFR after looking to Mr MJCronin 's respond.. English is not my first language . He explained and nailed the case with his own words.. Not only the content but syntax of his comment excellent..

I tried to give him three pink stars but not possible....

Quote (MJCronin ...This horse has been beaten to death ...)


We, the commenters did beat to death ..



RE: SHELL FINAL THICKNESS

(OP)
Sir lFRs,

It's ok, I understand. I'm just feel nervous when the time I found out that my tank design is still not ok. Since there's alot of design criteria I have to consider. Lack of design criteria is my problem from the very start, I know it.

I tried to tell this to my boss before, but it seems he don't have interest to email/contact our client to request the other design criteria. He always do nothing. For how many times. It also happen last time, when the client didn't give soil report.

Well that's him, not me.

Before you sent your last reply, I made a call to my boss. I told him that we need to request the other design criteria (internal, external pressure, and seicmic parameters).

Still, it seems he don't have interest or maybe he is shy to ask. And it seems he don't believe me that we need the complete data and the design criteria he gave to me is not enough.

Again, because their past designers can design a tank with only known dimension and location. Maybe he compare. But they're not me, I want more detailed.

Until I told him that I have some adviser from other country that gives me advice and told me that the tanks has lack of design criteria. Thankfully, he listen to me.

Sir maybe yes, maybe I'm not sure if the tank will experience internal vacuum. My basic criteria is, if it has vent then no internal vacuum. If no vent, internal vacuum will occur.

I'm sorry Sir, this is very very very completely different from what I dreamed for. I fell inlove in structural engineering when I was a college student and until now. But not for tanks, no disrespect for tank designers. Designing a tank is awesome but I love more to design buildings structures and that's makes me very happy.

API 650 is completely different from what I have learn in college Sir. I believe that every civil engineer will agree if they read this. Every sentence, every terms are completely different. I feel like a little bit of thermodynamics (basic mechanical engineering).

Again it's pandemic. I just keep fighting for my family. I'm just wait for the right time and look for other company.

Just like what I have said Sir. I only know about 1 foot method, variable point method, bottom plate, roof plate, rafter spacing, Annex A, B, E, K, S, V of API 650. I'm very sure in every value in my calculation. But I'm not sure if it's ok to use a certain annex for this tank. Yes Sir, I only used Annex S and V.

I'm not asking how to use 1 foot method Sir, I'm just telling how I used it. That is misunderstanding. I read some thread about full of water and that's confused me about 1 foot method. (https://www.eng-tips.com/viewthread.cfm?qid=165346)

Yes I know Sir. 1 foot method is very simple. I understand it, even how formula derived. It is from engineering mechanics - pressure vessels.

I'm a newbie that willing to learn and to be train. I'm sorry Sir, and I understand you. It's ok.

Thank you.

RE: SHELL FINAL THICKNESS

(OP)
Sir HTURKAK,

Thank you for your response. I really appreciate it. I will read those sections/annex you referred.

Wind velocity is 290kph. Yes sir.

The tank content is water Sir.

RE: SHELL FINAL THICKNESS

(OP)
MJCronin,

What's wrong with you. I did nothing to you.

Karma will take care of you.

Goodluck.

RE: SHELL FINAL THICKNESS

Lord Ets ...

Our interaction has nothing to do with Karma ... I wish you no harm, I have done nothing and I am sorry that I have offended you with my implied tone and word usage

You go to the Eng-tips website and ask a group of cranky retired strangers what their opinion is on a certain technical matter

They tell you ...

You ask them to to work for you, to educate you.. to expend their valuable time explaining things to you

They do ...

You pay nothing .... you offer nothing except more questions.

I am sorry about your personal situation, but many of us have been there too.... In the mid 1970s I have been broke with a wife and child to support and had to find a new job in a new state and new city with no money.

We have cautioned you about your boss and how he will try to control the design yet pin all responsibility on you ...

Perhaps you should look for another website where you can get superb quality advice and your feelings will not be hurt...

My opinion only

MJCronin
Sr. Process Engineer

RE: SHELL FINAL THICKNESS

We like to help people who came with pointed question, took the advice, and show progress before bring on the next question. You have a series of questions, but zero progress. You shouldn't stop work because the inaction, and lack of attention, from your boss, instead you should come up a frame work for him to comment on. He's job is managing, not babysitting.

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