2The Problem Current Wording: API Spec 6A 20th Edition, Annex M, “Qualification of heat-treating equipment”, Section M.3.3, “Temperature survey method for calibration of batch-type furnaces”, states the following in the 7th Paragraph:“When a furnace is repaired or rebuilt, a new temperature survey shall be carried out before the furnace is used for heat treatment.”The Problem:This implies a time-consuming and costly full survey is required, even for minor repairs to a furnace that will in no way affect the calibration or temperature uniformity in the furnace.
3The Solution Proposal: Revise API Spec 6A 20th Edition, Annex M, Section M.3.3, 7th Paragraph to the following:“When a furnace is repaired or rebuilt, a new temperature survey shall be carried out before the furnace is used for heat treatment, subject to the following. Repairs that return the furnace to the condition it was in at the time of the last furnace survey and calibration or repairs that do not affect the temperature tolerance of the furnace shall not require a new temperature survey and calibration. The SAE AMS 2750 sections on furnace modifications and furnace repairs shall be used to determine whether a new furnace survey is required.”
4The Solution Justification: There is no need to perform a costly and time consuming new temperature survey and calibration after repairs that do not affect the temperature tolerance of the furnace.Other recognized industry standards for furnace calibration permit such repairs without re-calibration. These include:SAE AMS 2750D