Interpret the Specs

In "Joe-6-pack-speak" it's close enough.

Density means it will float, barely. Less than 1=float:more than 1= sink.

Heat deflection won't be a problem in cold water.

All the rest you can ingore.

<Edit.> Well not a direct replacement, but it should work. Steel IS stiffer.

Well, that is pretty simple. Nuf' said.

Thank You.

While I am not a wood expert, I read specs nearly everyday. It has been my experience that when a spec is this detailed, someone has copied a manufacturer's spec sheet to the "T". At least, that is so in electrical work. I often see very detailed specs like this on VFD's and I have used enough of them, that I can usually say - yeah, they copied "XYZ's" data sheet right from their site. I suspect if you check around to various manufacturers of plywood you will find this published somewhere. (people writing specs usually aren't that knowledgeable) Don't know if wood is like electrical things, but usually it also stands that the various manufacturers will copy each other so that the product of company "X" will stand up to that of company "Y", on competitive models, so your supplier can probably verify if they match this. Check with them and save yourself the time to go surfing the net for this spec sheet.

thank you.

I don't know what electricians do, but I can tell you that the specifications of plastic materials are not coppied and re-used by the competition.

Ive got a fair amount of time (20 years) spent developing, specifying and even applying polymeric materials and exotic metals to space and terristrial equipment.

I've worked with Dow Corning, Dow Chemical, 3M, Loctite etc.etc.etc developing new materials and specifying existing materails and I can tell you for a fact that they do not do this coppying of material specifications.

Well...I look at spec packages for process equipment as part of my job. I get three kinds of packages:

1. Three pages describing the whole machine where the customer knows nothing and wants us to design it.

2. Thirty pages with specific model numbers where the customer knows exactly what he wants

3. Three hundred pages from a national engineering firm the customer has hired because they don't trust their own engineering staff. This firm has assigned a junior engineer to the electrical portion of the package and he/she wants to impress someone, so they don't list a model number - they go to the manufacturers site and copy the most detailed data sheet they can find and use up 2 pages on the description of a simple panel meter. There is also a second reason for this style of spec - eliminate the small jobber who gets bogged down on these specifics, when a simple model number would suffice and allow him to quote.

Now maybe this spec is for real, as you imply, but it sure strikes me as one of the third option above. Why not just say manufacturer "CDE" model "GHI" or equivalent? I usually end run the middle man in this case and go directly to the engineering staff of the customer and ask them what they want - it tends to save a lot of revising of the quote and job cost adders when we find what the customer truly wants. If this truly is a unique specification, shouldn't the specifier first be going to the plywood manufacturers to see if it can be manufactured, then pass this along to the builder? I would buy this is a very critical, well researched spec if this was the plywood manufacturer's question, not a builder using plywood.

Well, I built process equipment for 8 years, so I've seen both sides of the ditch.

Depends what you are making. I'd never buy anything for orbital platforms that wasn't specified, certified and inspected.

"GHI, or equivalent" is worse than useless, because it implies to me that the manufacturer doesn't know his product line and doesn't want to be bothered testing and properly characterising his products.

Specifications represent the minimum values you should expect. Anything over that is a plus. The following link will give you all the specs for different types and grades of plywood. http://www.apawood.org/level_c.cfm?content=pub_ply_libmain

That is something I never knew about. Thank you.

In my opinion, an important parameter is to compare the number of laminations between the two products. More laminations are usually better because the properties are more uniform in all directions (isotropic)..

The material I am looking at is not laminated as far as I can determine. It is solid and looks extruded.

So you are proposing to use an engineered material in or near water. If the adhesive they use becomes soft or damaged in water, you may change your mind. I have known several people who have built decks out of engineered lumber and have had them absorb water in wet weather and split when the weather turns cold. Also, if the material is exposed to sunlight it can become damaged by UV. I suggest you check out these properties. Manufacturers sometimes inundate you with so many specifications that you become saturated and overlook the most important ones.

This is not an "engineered" material. I think he's considering using solid polyethylene or PPRO instead of marine grade plywood.. Water exposure should not be an issue.

Correct.

PPRO is usually polypropylene, not polyethylene. To see the difference, Google the two with difference at the end. Some properties are remarkably different. Choose wisely.

Yes, "solid polyethylene or PPRO is what I said. "Or" being the operative word.

By the way, both are polyolefins. They do have different, and similar properties.

I have used them both in many applications from injection molded parts to vac formed parts, blow molded, blown film and bag making to 1 inch thick sheets used to build wet chem process (Etchers/developers/strippers and other) equipment for PWB fabrication. I understand the difference, trust me.

I should have spelled it out.

All those ASTM D### documents tell you what flexibility, hardness, etc. mean for the specific test methods described in those particular standards. Some of them will require special test equipment which you may not have. If you want to compare your Marine plywood to this material, this table plus the ASTM standards provide a way to make that comparison.

This is the kind of spec sheet you would give your supplier so that he knows what he has to deliver. Using an industry standard like ASTM has contactual advantages in that, as recognized industrial standards, they are readily acceptable in court disputes.

If future legal claims are not an issue, or you are still defining your requirements, just take a sample of your usual stuff and compare it against the unknown stuff using conditions you know make sense for what you do. If you do not have requirements for all these characteristics, don't sweat it. Identify what's important to you and just compare those points.

I believe I have enough information and the new material is very much sufficient to do what i need.

Thank you.