Interpretation ID: nht91-7.14

DATE: November 18, 1991

FROM: Eileen Mathews -- Industry Manager, Hose and Tubing, General Electric Company

TO: James Scapellato -- Director of Motor Carrier Standards, Federal Motor Carrier Highway Administration

COPYEE: Vernon Bloom; Ralph Ford; Mike Martin; Paul Brennan; Deirdre Fujita; Larry Minor

TITLE: None

ATTACHMT: Attached to letter dated 5/11/92 from Paul J. Rice to Eileen Mathews (A39; Std. 106)

TEXT:

GE Plastics is working with certain tube manufacturers to supply them with a high performance co-polyester engineering thermoplastic resin, under the tradename LOMOD resin, for use in the airbrake tubing. LOMOD resin would be sold to the tubing suppliers who would extrude the material and supply the brake tubing systems to the truck OEMs. GE Plastics is requesting an interpretation of Motor Carrier Specification 393.45 and DOT 571.106 in regards to GE Plastics ability to supply this market provided positive test results in accordance with DOT 571.106 and/or the SAE J844.

At this point in the airbrake program, GE Plastics has tested Type A 1 /4" tubing made from LOMOD resin per SAE J844 and DOT 571.106 (tubing tests but not assemblies). Tubing made from LOMOD resin has passed all relevant tests except that we have not yet tested UV with various colors. As GE Plastics commits money and resources to supply material to the airbrake tubing market, it is important that clarification is received on the following points:

The Motor Carrier Spec 393.45 refers to the SAE J844 Spec.

The SAE Spec includes a series of test requirements but also specifies tubing construction to be "a single wall extrusion of 100% virgin nylon (polyamide)". This material is sole sourced by one company, AtoChem. GE Plastics is interested in maintaining high performance standards, in the marketplace and believes that it has products which meet or exceed all current brake tubing performance standards, but GE Plastics does not supply virgin polyamide resin.

Question: Is it the Federal Highway Administrations intention that the regulations be interpreted as material specific and prohibit the use of resins other than "a single wall extrusion of 100% virgin nylon 11 polyamide" which may meet or exceed the performance requirements of the regulations? If not, will tubing be made of LOMOD copolyester material be in compliance with the Administration if all of the test requirements of SAE J844 are met (i.e. specification to read "J844 Tests" rather than "J844")?

The DOT Spec 571.106 makes reference to "coiled nylon tube assembly which meets the requirements of 393.45" in S7.3.6, S7.3.10 and S7.3.11. This reference or exemption with coiled tube is necessary for thermoplastic tubing (versus the original straight, rubber hoses) to meet the describe fitting pull-off tests.

Question: Does compliance with 571.106 require compliance with 393.45 and hence SAE J844? Is it necessary to call out "nylon" in S7.3.6 and S7.3.10?

Aside from exact material (polyamide resin) reference, the section detailing Construction in SAE J844 limits the make-up of the tubing by calling out "single wall extrusion".

Question: Does this prevent the supply of a co-extruded tubing (e.g. a possible VALOX polyester resin/LOMOD resin co-extruded tubing) which possesses the required I.D. and O.D. dimensions and which also passes all SAE J844 specification testing?

Our understanding is that the above questions will not to be addressed by SAE. The SAE Committee is a standardization committee which originates once a product is already on the market. It is likely that an SAE committee will write a new specification based on the new thermoplastic tubing passing the same testing criteria once that tubing is sold on the market. The new tubing, however, must be in compliance with DOT before it can be sold in the marketplace. Thus, unless Motor Carrier Spec 393.45, DOT 571.106 and the SAE J844 Spec are interpreted to allow the use of resins other than nylon, which also meet or exceed the performance requirements of those specifications, there does not seem to be a practical way to introduce a new competitive resin into the brake tubing application. We assume that it is not the intent of the regulators to restrict either the development of new technology or competition. Your clarification and response to this request will be appreciated.