According to the National Corn Grower’s Association’s annual report, 13.9 billion bushels of corn were

grown in the United States during 2013. That’s 32.1 percent of the world’s corn, making the U.S. the biggest

corn-producing nation. U.S. farmers also grew around 3 billion bushels of soybeans and over 2 billion bushels

of wheat.

If we assume an average weight of 60 pounds per bushel for these three crops (60 is the accepted average

weight for both soybeans and wheat; corn varies between 56 an 70, depending on whether it is shelled

or not), that’s somewhere in the neighborhood of 948 billion pounds of material. That’s just scratching the

surface of the grain industry, which also includes oats, rice, rye, and sorghum, among other, less-prevalent

grains.

This vast amount of grain needs to be harvested and processed, which means that it needs to be transported.

And all of the equipment used for grain conveyance needs to be able to stand up to some pretty rough

conditions as billions of pounds of material scrape, slam, and slide across it.

Grain silos, for example, are constructed out of incredibly durable material, often featuring cement walls lined

with hardened ceramic tiles. But for those spots where grain needs to move — such as bins, chutes, hoppers,

and spouts — other materials are preferable. These transitions need to be made out of more pliable material

like steel, which can wear out much more quickly than one would like. Replacing steel equipment can be costly

and time consuming.

That’s why wear-resistance solutions are important for every piece of

conveyance equipment in the grain industry. Many different approaches

to this problem have been developed over the years, but when one

considers all the options, it becomes apparent that urethane is the best

wear-resistant material available for grain-industry applications for a

variety of reasons.

For one, polyurethane’s ability to absorb impact — long recognized by the

mining industry for its wear resistance — makes it an excellent material.

Too, urethane makes a great material thanks to its incredible abrasion

resistance. The material really shines is when it is used as a lining material

to protect spouts and chutes — the most prevalent and vulnerable pieces

of grain handling equipment.

URETHANE WEAR SOLUTIONS FOR THE GRAIN INDUSTRY

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Metal grain conveyance equipment undergoes a lot of wear and tear but can be protected with durable lining material to extend life.

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WHY URETHANE EXCELS AS A LINING MATERIALBefore we begin to review the different lining options available, we should establish why one needs liners in

the first place. A simple analogy is to think of a grain conveyance system like a car. Sure, you don’t need to paint

your car, but it will definitely last a lot longer if you do. Lining, like paint, is fundamentally about protecting

your investment.

Once you accept that you need lining, it becomes a question of what type of material you want to use. You

can go with a cheap covering that will last for a little while, or you can invest in some higher-grade materials.

Below is an assessment of the most common options available.

CERAMICCeramic is incredibly wear resistant — it can be nearly as hard as diamond. This makes it great for

applications where abrasive material, such as grain or coal, slides and flows.

But ceramic is also inherently brittle, which causes it to break frequently during installation. This

relatively high level of waste, coupled with ceramic’s notably steep price, makes ceramic very

expensive to install and maintain. You also don’t want ceramic chips to end up in grain that’s intended

to be used as food — for either humans or animals.

AR STEELOne way to preserve your metal conveyance equipment is to line it with metal specially engineered

for wear resistance, such as abrasion resistant (AR), high-carbon steel. Admittedly, AR plate does a

good job and is generally 15 to 30 percent less expensive than urethane. But AR plate requires skilled

welders to form and install it, which also costs money. Urethane, on the other hand, doesn’t need to

be rolled or welded. It is pliable, forgiving when it comes to fit, and can be cut and bolted by almost

any handy employee.

Too, when you start thinking forward to replacement, the little extra investment in urethane will

really pay off down the line since urethane typically lasts longer than AR steel. It’s also a lot easier

to replace since it is light enough to be lifted without cranes. And unless you choose to use urethane

sheeting that attaches to equipment with welds (see below), it doesn’t invite the explosive danger you

may encounter when you light a welding torch near a grain silo.

UHMWFor some reason, roughly 20 to 30 years ago, UHMW manufacturers began marketing polyethylene

plastic as a lining material for grain conveyance systems. The fact is, UHMW is not suited for any

wear application except sliding wear, such as that created by boxes moving along a tray in a shipping

operation.

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Like ceramic, UHMW simply won’t stand up in impact situations. Unfortunately, people who tried

UHMW in the grain industry found this out first hand and this experience turned them off of plastics in

general — including polyurethane, which is an entirely different plastic substrate designed specifically

for impingement wear.

URETHANEOne of urethane’s defining characteristics is its ability to resist wear, especially abrasion and impact,

which makes it an exceptional lining material for grain industry equipment. Urethane will outwear the

steel most equipment is made from eleven to one. And it will last longer than the best AR plate lining,

which is the only other lining that really comes close to competing with it.

Compared to AR steel, urethane really shines when you consider the cost over time. For one, because

urethane needs to be replaced less frequently, it’s inherently less expensive when you take the long

view. But it is also easier to replace, meaning that retrofits will be less expensive and systems will be

subjected to less downtime whenever updates are required.

Urethane also has a final benefit that other materials used to line grain handling equipment don’t:

It insulates. Conveyance systems lined with polyurethane emit less noise as grain crashes and flows

through them.

URETHANE LINERS FOR GRAIN SPOUTS

Equipment owners, contractors, and spout manufacturers in the grain industry are typically looking to line

square or rectangular spouts. Usually, they will buy sheets of urethane in standard dimensions to cut and fit

to their particular conveyance systems. The standard sizes most often requested are 4’x8’, 4’x10’, 5’x8’, and

5’x10’.

Spouts with curved profiles, however, come in a variety of sizes that don’t quite line

up neatly with the standard sheet sizes. Rolls of urethane sheeting can be cut to fit

any curve, but it’s best to consult directly with a custom urethane provider when it

comes to round spouts.

FASTENING SYSTEMS FOR POLYURETHANE LININGFastening urethane lining to grain conveyance equipment is typically done with

elevator bolts, making installation a relatively straightforward process. This method,

however, is not the only option available, nor is it ideal since the protruding bolt

heads often catch pieces of grain, creating wear areas in the system. Below is an

explanation of three alternative fastening options, all of which have specific benefits.

WEDGIE BOLTSWedgie Bolts are elevator bolts that have been modified specifically to

secure urethane lining to grain spouts. Essentially, Wedgie Bolts are screws

with urethane-capped heads. To use them, drill an appropriately sized hole

for the bolt in the urethane sheet and the spout it is meant to cover. Then,

Urethane sheets are available in standard sizes for the grain industry.

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screw the nut on the bolt so that the head is flush with the

urethane sheet. This prevents any dip or discrepancy in height

between the sheet and the bolt head, creating a smooth surface

and minimizing any potential for wear.

FABRIC BACKINGPolyurethane sheeting can be manufactured with a fabric

backing, enabling you to glue the sheeting to your chutes, rather

than bolting or welding it in place. This technique is popular for

covering round spouts since it allows you to make the lining

conform to the curve of the spout, creating a continuous, uniform

bond with the surface. Gluing is also the preferred method when

you want to use longer, larger pieces of material — for example,

10’-long sheets.

With minimal seams and no holes once attached, fabric-backed

urethane sheeting can be used to create the most wear-resistant

surface possible while sparing your equipment the holes that come with fastening bolts.

FURTHER CONSIDERATIONSThis paper has focused mainly on polyurethane lining

for spouts, the most common type of grain conveyance

equipment. Urethane wear solutions are also available

for the myriad of other types of grain industry

equipment, including discharge chutes and pans,

hoppers, and holding bins, as well as rail car and truck

beds. Because the shapes and sizes of these types of

equipment vary so much, polyurethane lining generally

must be specially engineered for them, which requires

consultation with an experienced urethane provider that

has custom molding capabilities.

To learn more about custom solutions for the grain

industry, or to find out more about some of the standard

products for the grain industry discussed above, please visit us at www.baileyparks.com .

If you’d like a custom consultation or simply have a question about what you’ve read, you’re welcome to call

us at 1-800-966-2410. We’re happy to help develop solutions for any wear issues you may be facing.

Precision-cast urethane sheets can be made for grain industry applications that require non-standard dimensions.

Custom urethane wear solutions can be devised for rail cars, truck beds, and other, more complicated pieces of equipment such as discharge chutes, bins, and hoppers.