Partial-joint-penetration grooves · Clause 5
How do you determine PJP effective size?
For a prequalified PJP groove weld, effective size S comes from the matching Figure 5.2 detail. It is not automatically the groove depth D, the plate thickness, or the filled groove dimension. Select the exact process, detail, position and notes first.
A reliable reading path
- Confirm that the design calls for PJP and identify the member relationship: butt, corner, T or combined.
- Select the applicable Figure 5.2 row by designation, process suffix, unit system, position and thickness conditions.
- Read the groove dimensions and the row's effective-size equation. For two-sided details, calculate each side as instructed; do not assume equal depth.
- Apply the row's notes, such as drawing-depth requirement, each-groove calculation or flush-to-surface assumption.
- Compare the resulting S to the design-required effective size and the applicable Table 5.8 minimum, while checking fit-up tolerances and the rest of Clause 5.
Two Figure 5.2 rows show why S is detail-specific
| SI Figure 5.2 row | Selected detail conditions | Effective size | Important linked checks |
|---|---|---|---|
| BC-P2, SMAW | T1≥6 mm, T2=U; R=0; f≥1 mm; α=60°; all positions | S=D | Notes b, e, f, j; drawing must state D under note f, and Table 5.8 / applicable minimum-size rules still apply. |
| BC-P2-GF, GMAW/FCAW | T1≥6 mm, T2=U; R=0; f≥3 mm; α=60°; all positions | S=D | Notes a, b, f, j. It is a different row with a different root face and process condition. |
| B-P3, SMAW | T1≥12 mm; R=0; f≥3 mm; α=β=60°; all positions | Total S=D1+D2 | Notes e, f, i, j. Each groove's effective size is calculated separately; drawing depths and total design size remain necessary. |
| B-P3-GF, GMAW/FCAW | Same listed SI geometry as the SMAW B-P3 row | Total S=D1+D2 | Notes a, f, i, j. The same displayed geometry does not erase the process-specific note set. |
For a bounded arithmetic illustration only, if a matching BC-P2 drawing specifies D=8 mm, the row equation gives S=8 mm before checking the design demand and applicable minimum. For a matching B-P3 drawing with D1=6 mm and D2=8 mm, total S=14 mm. These values illustrate the equations, not a selected or approved joint.
Check minimum size separately
Table 5.8 gives PJP groove minimum effective sizes for the specified detail families. The SI entries are 2 mm for T1 3–5 mm; 3 mm for over 5–6 mm; 5 mm for over 6–12 mm; 6 mm for over 12–20 mm; 8 mm for over 20–38 mm; 10 mm for over 38–57 mm; 12 mm for over 57–150 mm; and 16 mm above 150 mm. The US column has its own inch bands and rounded values; use the contract's governing unit system rather than converting a boundary by arithmetic.
The table applies only to the indicated PJP types (2–9); square-groove and flare-groove details use their Figure 5.2 row rules. The minimum also does not replace the drawing's design-required size. Depending on applicable notes and loading rules, S need not exceed the thinner member thickness, but that ceiling does not authorize reducing a larger design demand.
Where a PJP conclusion stops
- Clause 5.4.2.3 does not set one general maximum base-metal thickness for PJP; each detail's minimum member thickness, geometry, process, temperature and other applicable requirements still bound it.
- For most PJP details, the drawing must give groove depth D. The listed exceptions are B-P1, BTC-P10 and B-P11; do not extend their exception to other details.
- With two grooves, note i calls for the effective size of each groove to be calculated separately. The sum is used only where that row defines total S that way.
- For joint families 2–9, Table 5.8 and the row formula are separate checks. Do not apply the table to an unlisted family or substitute D for S without figure support.
For CJP groove selection and backing, see the CJP guide and the backing decision guide. PQR-supported PJP procedures follow their qualification path and should not reuse Clause 5 figure assumptions without review.
Code basis and limits
Basis: AWS D1.1/D1.1M:2025 base edition plus registered base-edition errata dated July 28, 2026; AMD1 is not included. Principal provisions: Clause 5.4.2, Figure 5.2 BC-P2 and B-P3 details (including the row geometry, construction, tolerances and notes), Table 5.8 and the applicable minimum-size provisions.
This guide explains how to read a detail; it does not determine structural adequacy or approve the specified weld size. Use the complete controlled standard, drawing and project requirements for a production decision.
Provide the drawing, effective-size requirement, selected unit system and governing edition.