Difference Between Sheet and Plate Terms Used in Sheetmetal Fabrication

Plate isn't used in sheet metal fabrication.

There may not be any absolute rule, but plate commonly starts at 0.25" thickness and above. Below that, gauge numbers are often used, at least in the U.S. There may also be some historical practices such as sheet being offered in hot-rolled, cold-rolled, galvanized or not, coiled, etc.

sheet thickness is measured by gauge, while plate thickness s measured by inches or MM.

There is a transition such as 7 gauge is approx. (.187) and 3/16" plate. Also gauges varies on material type.

Don't know the history of how or why.

Can you explain what you mean by, "Also gauges varies on material type."?

Sure, Gauge thickness varies between material types…… Such as Stainless, Aluminum, Carbon Steel, Galvanized Steel, Aluminized Steel… all different.

And the usage of gauge material for thickness is discouraged by various international standards organization because they is no agreement on a standard.

Thanks.

There is little scope for fabricating a pressure vessel out of sheet.

Never under estimate the scope of some people posting questions on CR4. There seems to be an inverse relationship between knowing what you are doing and the scope of what some people do. I just hope I am well down range when their project has a reality discontinuity and a subsequent rapid disassembly.

Quite. Catastrophic self-disassembly is best viewed at a distance, possibly with binoculars.

and some type of video recording device.....

Are we tripping across a revenue stream for CR4?

Free advise comes with a web cam. Use web can when using free advise. CR4 can YouTube the video's and collect on the sidebar "click per view" advertising.

Dear Mr.saravanan040319,

Generally Sheets can be rolled but not plates. Sheet size is smaller in terms of length and width, where as it is large for plates. Thickness is expressed in SWG. Sheets cane be cut by heavy duty cutters, but not plates. Where Tinkering is adopted there the terminology SHEET is used.

DHAYANANDHAN.S

The shouting is not appreciated; nor various inaccuracies.

er, not true at all, plate is often rolled into cylindrical sections... we used 1/2" plate rolled into cylinders ranging from 32" all the way up to 72" o.d. at my previous job manufacturing reels for offshore drilling umbilicals. There is a little bit of overlap between plate and sheet in the 3/16" thickness, but from 1/4" and up, it is all plate. Plate usually has a specification for impact toughness which is not specified in sheet typically. Chemistry, cleanliness, grain structure, and heat treating is often controlled much closer since plate is almost always welded. Plate, especially thinner plate can be obtained in coil form for long fabrications. we buy plate and convert it to OCTG pipe where I work now.

In the shipyard this can be pretty common.........

Same answer but not off-topic.

Our steel supplier in the old days differentiated by saying the 'sheet' came off a roll that he cold straightened and cut to (my) size. Whereas the 'plate' he supplied came from the hot mill ready cut in flat sheets (the plate was supplied in sheets - already a contradiction in terms). I didn't give the matter much thought.

But it seems from inputs to this OP that it is largely a matter of opinion.

With a line drawn somewhere quite arbitrarily on hickness, and maybe 'flatness'.

I found the Wikipedia definitions and information on "sheet metal" really accurate, but what do I now, I've only been in fabricating steel (both plate and sheet) for 40 years. Read it and learn.

Well Wiki is ok, because is saves time from listing 40 years of experience....

Yes indeed it does save my time. Why try to explain the "wheel", when it has already been done. All one can do is try to improve on it.

There are industry variances on these definitions. Where I work, the US aviation industry, sheet is 0.249" and below, plate is 0.250" and above.

This is governed by a document called MMPDS (old Mil-STD-5 handbook) that is edited by Battelle Labs and authorized by the FAA.

We, in aviation, do not describe sheet requirements by gage. We specify by nominal thickness; typicaly, .03, .04, .05, .06, .07, .09 and .125.

In other words make sure you understand your industry custom and norms.

Hooker

The difference is the method of manufacturing. As used in our industry, sheet encompasses anything less than .188" - plate starts at .188" and goes up.

Plate gauge thickness can be achieved using a hand mill for thinner material (passing the plate back and forth manually) thru a roll pack to get the final thickness. Thicker gauges use an automated rolling system to pass the plates back and forth thru the roll pack.

Sheet thickness is achieved by running the material thru a series of roll packs back to back (material is pulled thru the rolling process in one direction only).

Flat bar is also called plate by some.

I often see fractional sheets regarded as plate and sheets defined by gauge as sheet.

As flat bar is covered by the same ASTM standard as plate, (A36 typically) that makes sense to lump them together.

I think the thickness difference has been well covered.

Re the "Is there any specific reason to differentiate between sheet and plate and why is it differentiated?":

I think it's got to do with the older trades who dealt with these materials and the equipment and tools that they use, for example you won't find a sledge hammer in a sheetmetalworker's tool kit - instead he'll have a planishing hammer and vice versa for the boilermaker.

Following my previous post at 16, is 'flatness' a factor?

Is it accepted that sheets and plates are flat. Is flatness intrinsic in the rolling process related to whether it is plate or sheet, or is it something that has to be specified if it matters.

How is flatness specified, or measured, or checked for quality control?

Slightly off-topic I bought some cheap 900mm x 10mm round bar tie rods, and they were curved (obvious to the naked eye and looked awful). The supplier said they were made from 10mm wire pulled off a coil and straightened (well not quite I thought), then cut and threaded. "...they straighten out when under tension..." was the glib response to my complaint. "..you didn't specify straightness...".

I didn't specify 'straightness' when I bought round bar when I made my own tie rods. The round bar was perfectly straight.

The cheap rods were OK in all respects, but looked awful. The only endearing feature of the 'curved' rods was that they didn't roll off the bench.

Back to sheet and plate, how 'flat' is it.

Plate also go through a rolling procedure for stress relieving.

Nothing worse that putting a plate on a cutting table, (Plasma, laser or waterjet) and as you are cutting it the plate curls up. and possible snapping the head off.

Dear All

-Would like to introduce some old (but good...) DIN definition of sheets/plates ;

It is classified in 3 ranges: DIN-1541/1 From:0.18mm to: 3.0mm H.Rolled,for coating

DIN-1541/2 From:0.18mm to: 3.0mm Cold Rolled,for drawing

DIN-1542 From:3.0mm to: 4.75mm,H.Rolled ,"Middle sheet"

DIN-1543 Above;4.75mm H.Rolled steel plates for any purpose

-It was based on the fabrication +use of this sheets / plates

Good DIN information, thank you.

My company builds vessels from 8" to 144" using inch dimension plate such as 1/2", 1", 2", to 4" thickneses.

We outsource the fabrication to ASME "UM" stamp of gauge vessels such as 10ga, 12ga, to 22ga. the with 150 psi ASME Registered vessels as thin as 0.094" thickness, similiar to the compressed air tank business.

Some of the raw material is decoiled, flattened, then the cutting we see during shop audits of gauge material being cut under water leaves the plate as flat as what it is laying on when cut or after the cuts are finished.

In the shipbuilding industry, sheet is any thickness less than 1/8". Sheet is designated by gauge. Steel plate is designated as pounds per sq ft. Aluminum and stainless steel plate is designated in decimal inches. Generally non-ferrous metals are designated by gauge.

I won't say that.....

That may have been the criteria at the yard where you worked,

we had 7 ga. and 3/16 plate........

And also, I noticed a lot of companies at Account Payable, I have seen how they track material have been in lb's for sheets and plates........

I worked in many shipyards in 50 years, both Naval and commercial. We always referred to 1/8" thick plate as 5.1 # and 3/16" plate as 7.65#. That is how it was listed in the Bethlehem steel handbook. That is how it was called out on engineering drawings.

on our internal requisition orders, we would call out for 304 SS?? 7 ga. and procurement would follow up and call us back, and 7ga is 3 weeks out, is 3/16" (with spec's) plate ok.......

And Vice-Versa,

The only thing where it may be critical is surface finish requirements......

#32, I agree, I deal with some of the larger structural fabrication companies who build to the MBMA and AISC Standards.

They calculate their daily fabrication totals to tons per day, seperating the Gauge material per AWS D1.3 decoiled, rollformed, welded, painted, etc.

With 3/16" and over plate to AWS D1.1 cut, formed, seamed, etc. task totals.

Keeping still seperate total for the ANSI beam, channel, angle, wide flanged tons per day.

trying to stay on topic....

Thanks,.......

This is all good to know, I developed a department, and I wanted to eliminate the redundancy on BOM's....... Engineering used sq. footage, and accounts used pounds......

I think this is on topic, its answering a lot of questions........ at least for me it is.

hhahah this is the only topic in cr4 ,there all the particepents have different concepts about sheet and plte.

in simple words , the sheet is cant be processed on the machine-tool(lathe,milling etc) and plate can be processed on that .

so the thickness counts ...........

That is also another opinion....... it depends on your organizations definition.