Can I substitute A563 nuts?
The ASTM specification for A563 Nuts allows certain substitutions under defined conditions:
Within A563 (Grades A → DH): The A563 specification states that nuts manufactured to a stronger grade within A563 may be substituted in place of a weaker grade. This means an A563 Grade DH nut can be substituted in place of an A563 Grade A nut.
Section 1.2 The requirements for any grade of nut may, at the supplier’s option, and with notice to the purchaser, be fulfilled by furnishing nuts of one of the stronger grades specified herein unless such substitution is barred in the inquiry and purchase order.
This allows the supplier (with notification to the buyer) to substitute A563 Grades DH for Grades A, B, C, and D because Grade DH is stronger than each of them.
Across specifications (Grades DH → 2H): A563 also makes a special provision that allows substitution of A563 Grade DH nuts with A194 Grade 2H nuts.
Table 3 Note D: Nuts made in accordance with the requirements of Specification A194/A194M, Grade 2H, and marked with its grade symbol are an acceptable equivalent for Grade DH nuts.
In practice, this means:
You can move upward within the A563 family (e.g., from Grade A to Grade DH).
You can also move laterally across specs in the specific case of Grade DH to Grade 2H.
Combining these readings allows moving from A563 Grade A to A194 Grade 2H.
We recommend confirmation with the project specifications or the engineer of record before making any substitutions. However, these ASTM specifications clearly approve such substitutions, and in the case of substituting higher strength A563 nuts for lower strength nuts, the specification empowers the nut supplier to make that substitution. If you need bolts and nuts for an upcoming project, please reach out to one of our experienced account managers.
