Accurate monitoring of corrosion rates in any environment is critical when viewed in terms of the maintenance and repair costs associated with corrosion and material failure. Test coupons provide an inexpensive means of on-line monitoring that will allow you to effectively measure the corrosivity within your system. By observing the mils-per-year corrosion rate of an exposed coupon, valuable information can be provided regarding the material’s life expectancy. Biolab can make coupons in any size, shape, or material you need. Coupons can be stenciled with alloy and sequence numbers for proper identification. Mill test reports, identifying element compositions of materials used, are provided on all orders. The following coupons are four of the most commonly used in corrosion testing.
Coupon Ordering and Services Available
When placing your order for coupons, be ready to provide the sales person with information regarding the type of material you are testing, the size coupons required, surface finish desired, and if applicable, mounting hole size and location. The following options are available:
|P/N||Size||Hole||Hole Location||Area Sq. In.|
|CO100||1/2” x 3” x 1/16”||3/16”||1/4” fr. end||3.38|
|C0101||1” x 2” x 1/16”||3/16”||1/4” fr. end||4.32|
|CO102||1/2” x 3” x 1/16”||9/64”||1/8” fr. end||3.41|
|CO103||1/2” x 3” x 1/16”||1/4”||1/4” fr. end||3.34|
|CO104||1/2” x 3” x 1/16”||(2) 1/4”||1/2” fr. ea. end||3.24|
|CO105||1/2” x 3” x 1/16”||3/16”||1/2” fr. end||3.38|
|CO106||1/2” x 3” x 1/16”||1/4”||1/2” fr. end||3.34|
|CO115||1/2” x 3” x 1/16”||1/4”||1/4” fr. end|
|CO117||3/8” x 3 x 1/16”||9/64”||1/8” fr. end||2.64|
|CO118||1/2” x 3” x 1/16”||(2) 1/4”||1/4 & 3/4” end||3.24|
|CO120||3/8” x 3” x 1/16”||(2) 1/4”||1/4 & 3/4” end||2.48|
|P/N||Size||Thread||Slot||Area Sq. In.|
|ES200||1/4” x Ø x 2 1/2”||1/4”-20 x 3/8”||1/16”||1.96|
|ES201||1/4” x Ø x 2”||1/4”-20 x 3/8”||1/16”||1.57|
|ES202||1/4” x Ø x 3”||1/4”-20 x 3/8”||1/16”||2.45|
|ES204||1/4” x Ø x 1 1/2”||1/4”-20 x 3/8”||1/16”||1.18|
|ES209||1/4” x Ø x 3”||1/4”-20 x 3/8”||1/16”|
Fixed (Pipe Plug) Coupon Holders
Biolab carries a variety of standard pipe plug coupon holders for flat and cylindrical specimens. We can design and make these assemblies to meet your specifications for size and material requirements.
Pipe Plug Assemblies for Flat Coupons
|P/N||Plug Size||3” (Std.) Stem||Used with Coupon P/N|
|RC12E*100036||3/4” NPT||Nylon||CO102, CO117|
|RC13E*100036||1” NPT||Nylon||CO102, CO117|
|RC12Q*100036||3/4” NPT||Teflon||CO102, CO117|
|RC13Q*100066||1” NPT||Teflon||CO102, CO117|
|RC12E*010036||3/4” NPT||Nylon||CO100, CO103, CO115|
|RC13E*010036||1” NPT||Nylon||CO100, CO103, CO115|
|RC12Q*010030||3/4” NPT||Teflon||CO100, CO103, CO115|
|RC13Q*010026||1” NPT||Teflon||CO100, CO103, CO115|
|RC12E*030036||3/4” NPT||Nylon||CO118, CO120|
|RC13E*030036||1” NPT||Nylon||CO118, CO120|
|RC12Q*030036||3/4” NPT||Teflon||CO118, CO120|
|RC13Q*030035||1” NPT||Teflon||CO118, CO120|
|RC12E*090036||3/4” NPT||Nylon||CO105, CO106|
|RC13E*090036||1” NPT||Nylon||CO105, CO106|
|RC12Q*090036||3/4” NPT||Teflon||CO105, CO106|
|RC13Q*090036||1” NPT||Teflon||CO105, CO106|
|RC11E*010036||3/4” NPT||Nylon||CO100, CO103, CO115|
Pipe Plug Assemblies for Cylindrical Coupons
|P/N||Carbon Steel Plug||Insert||# of Stems|
Bypass Piping Systems
We provide conventional or custom-designed bypass systems for on-line corrosion monitoring. Commonly used in the industrial water treatment industry to determine the corrosive properties of potable or cooling water, these systems are available in PVC, carbon and stainless steels, and other materials.
Bypass systems are easily installed to your existing piping. Normally, all you need is a 1” NPT male fitting on which to attach the bypass. Standard bypass systems come equipped with 4 pipe plug assemblies, 4 pre-weighed mild steel coupons, and a 5-gpm flow control valve.
Adjustable Coupon Holders
Low Pressure or Hand Insertable systems can be used for pressures up to 125 psi. This assembly is commonly used in the water treating industry for coupon insertion through a full port valve. An example of this is in a municipal water pumping station, where leakage during withdrawal of the test coupon would not be critical.
Retractable Coupon Holders
Packing Gland systems are used in more demanding environments, where ratings up to 1,500 psi are required and leakage is prohibited. These systems do not require line (process) shutdown to insert or withdraw coupons. The assembly is used for coupon insertion through at least a 1” full port valve. A safety chain is provided to prevent accidental ejection.
Retrievable Coupon Holders
These coupon holders are used with High Pressure Access Systems where pressure ratings up to 3,600 psi are required.
Corrosion rates can vary between welded and non-welded metals, therefore it is advisable to study the behavior of both conditions. Studies involve examination of the parent material, the heat affected zone, the weld metal, and the interfaces between all metals involved. The surface effects produced by welding, heat-tint formation or oxidation, fluxing action of slag, and the deliquescence of slag can be important factors in the corrosion behavior of metals.
Ideally, the coupon used should be the same thickness and welded with the same welding process as the material used in the production equipment. Usually this is not practical so a representative sample must be studied.
Typical welding techniques used are Shielded Metal Arc (SMAW), Gas Tungsten Arc (GTAW), and Gas Metal Arc (GMAW). Specimens are ground smooth after welding, unless otherwise specified, so as to provide a uniform surface for microscopic investigation.
Biolab offers test racks used to mount coupons and secure them directly to operating equipment or within a process system. Test racks make it easy to evaluate how corrosion would effect differing alloys and material finishes under identical conditions. Rack usage helps eliminate coupon loss which might occur if samples were individually placed in a process flow.
Racks can be fabricated to meet your requirements for material and size. Typical racks are flat bar racks, spool racks, and pipeline insertion racks. Other racks include angle bar racks and outdoor exposure racks. A variety of insulators, washers, and spacers used to isolate coupons can also be ordered separately.
Guidelines for Supporting Specimens
Corrosive behavior of materials subjected to immersion, partial immersion, or vapor phase can have great variance. For this reason, specimens to be tested should be properly positioned. There are several important points to be considered when supporting specimens for exposure: