Interpretation ID: nht75-3.48

DATE: 12/29/75

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Truck Trailer Manufacturer Association

TITLE: FMVSS INTERPRETATION

TEXT: This responds to the Truck Trailer Manufacturer Association's November 17, 1975, request that the NHTSA reconsider its opinion that modification of existing tank trailers to increase their volumetric capacity and length does not constitute manufacture of a new air-braked trailer that must comply with Standard No. 121, Air Brake Systems. This opinion appears in a letter of August 28, 1975, to Stainless Tank and Equipment, Inc.

The National Traffic and Motor Vehicle Safety Act (the Act) authorizes the issuance of motor vehicle safety standards (15 U.S.C. @ 1392(a)) and prohibits, among other things, the manufacture of a motor vehicle on or after the date any applicable standard takes effect unless the vehicle conforms to the standard, and is so certified (15 U.S.C. @ 1397(a) (1) (A), 1403). With the 1974 Amendments, (15 U.S.C. @ 1397(a) (2) (A)) no manufacturer, distributor, dealer, or repair business may perform modifications that render inoperative any device or element of design required by a standard. However, unless the modifications performed are so extensive as to constitute legally the manufacture of a new vehicle, the standards that continue to apply to a vehicle are those in effect at the time of its original manufacture, not those that may have come into effect at a later date.

The modification of a tank trailer to increase its volumetric capacity and length does not, in our view, constitute the manufacture of a new vehicle in the typical situation (about an 18-inch increase in length). For this reason, Standard No. 121 does not apply to existing vehicles that are modified in accordance with your description.

This response does not address the issue of compliance with Federal motor carrier regulations raised in your November 17, 1975, letter.

SINCERELY,

TANK CONFERENCE

TRUCK TRAILER MANUFACTURER ASSOCIATION

November 17, 1975

MESSRS:

Dr. James B. Gregory Administrator National Highway Traffic Safety Admin. Department of Transportation

Dr. Robert A. Kaye Director Bureau of Motor Carrier Safety Department of Transportation

GENTLEMEN: There has been considerable discussion, correspondence, and individual rulings resulting from the legislation that liberalized weight laws at the same time the new braking standard became effective.

The central question is: If a tank trailer is modified to increase its load carrying capacity under the new weight law, must it also be modified to the latest safety standards?

Our industry, because of the type of materials handled in tank trailers that we manufacture, has always had a great deal of concern for the safety aspect of these tank trailers. This was certainly shown in the cooperation between the Tank Conference Engineering Committee and the Department of Transportation during the upgrading of the MC codes in 1967. We felt in tune with, and supported, the obvious objectives of the Department of Transportation to upgrade the safety of tank trailers on the highway. All tank trailers built to the previous less stringent specifications, such as MC 305, were to be gradually phased out through attrition and all new tank trailers built after 1968 would have to conform to the new and safer specification, such as MC 306.

The recent enactment of Public Law 93-643 enabling carriers to transport higher gross vehicle loads has raised two major questions:

(1) Whether a capacity increase in a tank trailer -- or "stretching" would require bringing the tank trailer up to the standard of the existing MC specifications (post-1968), irrespective of when the tank trailer was originally produced, and

(2) Whether this equipment when modified would require compliance with all current MVSS 121 braking standards.

There are additional questions such as whether the modified tank trailer would require recertification per current Motor Vehicle Safety standards, per latest Hazardous Materials Regulations and per ASME and National Board as applicable.

Some of the specific rulings or interpretations issued by various officials in the Department have stated that increasing the capacity of a tank trailer or "stretching" would not require bringing the tank trailer up to the current MC specification nor the installation of the MVSS 121 braking system.

This appears to be inconsistent with what we understood to have been the Department's previous intent, which we as an industry wholeheartedly supported. It appears that under this practice the pre-1967 specifications could be perpetuated indefinitely.

Since the shell of a tank trailer is also its sole structural support, special safety implications must be taken into account which do not apply to other types of trailers.

It is unanimous opinion of the Tank Conference of TTMA that any modification of a tank trailer that increases its volumetric or gross vehicle weight capacity should be permitted only if the tank trailer is brought to the current safety standards as reflected in the current MC specifications and MVSS 121.

Our Engineering Committee would be pleased to meet with you at your convenience to discuss these important items.

Charles J. Calvin President