How do I determine lot sizes for HDG inspection?

The lot size is an important component of HDG inspection because it is used to determine the total number of test articles and measurements required to ensure the quality of hot-dip galvanized coatings provided by the galvanizer.

However, sometimes confusion can arise as to what constitutes the definition of an inspection lot, especially for large orders where multiple material shipments of a single order are hot-dip galvanized over a period of several days, potentially using more than one kettle. Additionally, it may be required to differentiate between inspections performed at the galvanizing facility and by the purchaser after delivery.

The definition of an inspection lot size at the galvanizing facility differs slightly between the governing hot-dip galvanizing specifications (ASTM A123, A153, and A767).  Additionally, ASTM A123 is the only specification which identifies separate definitions for inspections performed at the galvanizing plant and by the purchaser after delivery. The definitions and examples below can be used to differentiate between the specification requirements.

Be on the lookout in the next few weeks for an upcoming Galvanizing Note which will cover how to determine HDG inspection lot sizes in more detail and include decision flow charts with detailed examples to be used for clarification. The Galvanizing Note will be distributed to all TechNotes recipients and will also be available for download on the AGA website. To be added to the TechNotes distribution list, please contact Alana Hochstein.

At The Galvanizing Facility

ASTM A123

The specification language used to describe an inspection lot at the galvanizing facility is as follows:

7.2  A lot is a unit of production or shipment from which a sample is taken for testing. Unless otherwise agreed upon between the galvanizer and the purchaser, or established within this specification, the lot shall be as follows: For testing at a galvanizers facility, a lot is one or more articles of the same type and size comprising a single order or a single delivery load, whichever is the smaller, or any number of articles identified as a lot by the galvanizer, when these have been galvanized within a single production shift and in the same bath. []

To condense the specification language, a lot, in this case, consists of:

• Articles of the same type and size comprising a single order or single delivery (whichever is smaller).
• And articles identified as a lot by the galvanizer when (both must be true):
  • The articles are galvanized within a single production shift.
  • The articles are galvanized in the same galvanizing bath.

For example, lets imagine that fifteen identical 20ft long pipes have been delivered in a single shipment to the galvanizing facility under one order.  Five pipes were galvanized on Day 1 in Kettle #1.  The remaining ten pipes were galvanized on Day 2, but five of the pipes were sent to Kettle #1 while the other five pipes were sent to Kettle #2.  As a result, three inspection lots are required for this order because of the two-day production span and use of two kettles.

ASTM A153

The specification language used to describe an inspection lot at the galvanizing facility is as follows:

3.2.5 inspection lot, n the quantity of identical parts cleaned, fluxed and galvanized together at one time in an appropriate container that is being submitted for acceptance as a group.

For example, a shipment of hardware that requires separation into four baskets in order to perform hot-dip galvanizing will constitute four inspection lots, regardless of whether the items were hot-dip galvanized on the same day or over a period of days.

ASTM A767

The specification language used to describe an inspection lot at the galvanizing facility is as follows:

4.2.3 Note 5 A lot shall be as follows:  All bars of one size furnished to the same steel reinforcing bar specification that have been galvanized within a single production shift.

By The Purchaser After Delivery

ASTM A123 is the only specification which differentiates between inspection at the galvanizing plant and by the purchaser after delivery.  The specification language used is as follows:

7.2  [] For test by the purchaser after delivery, the lot consists of the single order or the single delivery load, whichever is the smaller, unless the lot identity, established in accordance with the above, is maintained and clearly indicated in the shipment by the galvanizer.

To condense the specification language, a lot, in this case, consists of:

• The single order or single delivery load (whichever is smaller).
• The lot identity from the galvanizing plant when it has been maintained during shipping and clearly indicated (and meets the requirements above).