ASTM A991/A991M-98(2004)

Furnaces for heat treatment of steel products are used in many industries, in many ways. Regardless of heat treat furnace type, or processing cycle, it may be necessary for users to know the temperature uniformity in the furnace and whether the material is processed in a zone within the furnace that is capable of meeting the applicable permissible temperature variation requirements.

The procedures in this test method may be used by those using, manufacturing, and providing calibration service for, heat treat furnaces used to process steel products.

1.1 This test method covers the procedures used to conduct a temperature uniformity survey on a furnace used to heat treat steel products. This method is used to determine the capability of the furnace to meet the permissible temperature variation specified in the applicable product specification, or as agreed to by the purchaser and supplier of heat treat services. Survey documentation requirements, and the procedure used to subsequently establish the furnace working zone, are defined in this test method.

1.2 This test method covers heat treat furnaces in any of the following categories:

1.2.1 Continuous or semi-continuous conveyance furnaces,

1.2.2 Batch furnaces, and

1.2.3 Salt or liquid baths and fluidized beds.

1.3 This test method only applies when specified in the product specification or the purchase order.

1.4 Controlling a heat treatment of steel products using thermocouples attached to the extremities of each load is an alternative to performing a furnace survey.

1.5 By mutual agreement between the purchaser and the supplier of heat treat services, more stringent and/or additional requirements may be specified. The acceptance of any such additional requirements shall be dependent on negotiations with the supplier and must be included in the order as agreed upon by the purchaser and supplier.

1.6 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system is to be used independently of the other, without combining values in any way.

1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.