Type a line (U3 stud link 54 mm, Grade 3 studless 34, U2 d=46), or pick the grade and the link type and give the diameter. Below, an offered chain can be checked against the one wanted.
On the grade, the diameter and the link type alone: the length, end links, joining shackles and certificate are checked separately, and the certificate of the chain governs.
IACS UR W18 sets three grades of stud-link anchor chain cable, grade 1, 2 and 3 (often written U1, U2, U3), and gives the proof load and the breaking load of each as a function of the nominal diameter d in mm: the breaking load of grade 2 stud-link chain, for example, is 0.01373·d²·(44 − 0.08d) kN. Type a line such as “U3 stud link 54 mm”, or pick the grade and give the diameter, and the reader draws the links to scale, computes the proof and breaking load from the formula, gives the link proportions and the marking, checks an offered chain against the one wanted and writes an RFQ line.
The figures are computed from the rule formulas and rounded; they are not the figures of a particular chain. The certificate of the chain, issued by the class society, governs. UR W18 covers stud-link chain; for studless chain this reader gives no loads.
UR W18 divides stud-link anchor chain cable into grades 1, 2 and 3 by the tensile strength of the steel; they are often written U1, U2 and U3. The higher the grade, the higher the proof and breaking load at the same diameter: the breaking load of grade 1 is the proof load of grade 2, and the breaking load of grade 2 the proof load of grade 3.
A common stud link is about 6d long and 3.6d wide outside, with a stud across it; a studless link about 6d by 3.35d. UR W18 gives its formulas for stud-link chain. Studless chain, where the class society accepts it, is made to a recognised national or international standard, and its loads come from its certificate.
Anchor chain cable is made and proof tested in lengths of 27.5 m, called shackles, and joined by joining shackles (Kenter shackles). Each length is stamped at both ends with the grade, the certificate number and the class society’s stamp; the joining shackles carry the same marks.
| Grade | Proof load, kN | Breaking load, kN |
|---|---|---|
| Grade 1 (U1) | 0.00686·d²·(44 − 0.08d) | 0.00981·d²·(44 − 0.08d) |
| Grade 2 (U2) | 0.00981·d²·(44 − 0.08d) | 0.01373·d²·(44 − 0.08d) |
| Grade 3 (U3) | 0.01373·d²·(44 − 0.08d) | 0.01961·d²·(44 − 0.08d) |
| d, mm | Grade 1 proof | Grade 1 breaking | Grade 2 proof | Grade 2 breaking | Grade 3 proof | Grade 3 breaking |
|---|---|---|---|---|---|---|
| 16 | 75.0 | 107 | 107 | 150 | 150 | 214 |
| 20.5 | 122 | 175 | 175 | 244 | 244 | 349 |
| 26 | 194 | 278 | 278 | 389 | 389 | 556 |
| 34 | 327 | 468 | 468 | 655 | 655 | 936 |
| 42 | 492 | 703 | 703 | 984 | 984 | 1406 |
| 54 | 794 | 1135 | 1135 | 1589 | 1589 | 2269 |
| 64 | 1092 | 1562 | 1562 | 2187 | 2187 | 3123 |
| 76 | 1503 | 2149 | 2149 | 3007 | 3007 | 4295 |
| 87 | 1923 | 2750 | 2750 | 3849 | 3849 | 5498 |
| 100 | 2470 | 3532 | 3532 | 4943 | 4943 | 7060 |
| 122 | 3496 | 4999 | 4999 | 6997 | 6997 | 9994 |
Computed from the formulas of UR W18 Table 5 and rounded to whole kN; the certificate of the chain governs. Each coefficient is confirmed by the UR W18 text and by at least one more independent source: a chain cable maker’s table, the Russian national standard for stud-link anchor chain and a supplier’s table. Left out: the loads of studless chain in grades 1, 2 and 3 (UR W18 covers stud-link chain, and the sources checked disagree on studless figures); the offshore mooring grades R3, R3S and R4 (UR W22: the sources checked give different proof-load coefficients for R3); the tensile strength of the steel by grade (the figures for grade 1 differ between sources); the inside length of a studless link, the dimensions of the stud, and the proportions of enlarged links, end links and joining shackles; the weight per metre.
IACS UR W18 Rev.6 (2021), Anchor chain cables and accessories: Table 5, 4.1.2, 4.4 and 5.4; IACS UR W22 Rev.6 (2016), Offshore mooring chain, for the grades left out; GOST 228-79, the Russian national standard for stud-link anchor chain; the technical tables of a chain cable maker and of two mooring and chain suppliers, and the documentation of a mooring analysis program; a patent filing that sets out the link proportions of ISO 1704. Every coefficient and figure on this page is in at least two of them.
They are the three grades of stud-link anchor chain cable in IACS UR W18, grade 1, 2 and 3, set by the tensile strength of the steel. At the same diameter, a higher grade has a higher proof load and breaking load. Each length is stamped at both ends with its grade, the certificate number and the class society’s stamp.
UR W18 Table 5 gives each as a coefficient times d²·(44 − 0.08d), with d the nominal diameter in mm and the result in kN. Proof load: grade 1 0.00686, grade 2 0.00981, grade 3 0.01373. Breaking load: grade 1 0.00981, grade 2 0.01373, grade 3 0.01961. A 54 mm grade 2 chain therefore has a proof load of about 1135 kN and a breaking load of about 1589 kN. These are computed figures: the certificate of the chain governs.
No. UR W18 covers stud-link chain; studless chain, where the class society accepts it, is made to a recognised national or international standard. The sources checked here disagree on the loads of studless chain, so this reader gives none: take them from the chain’s certificate.
Anchor chain cable is made and proof tested in lengths of 27.5 m, called shackles, joined by joining shackles (Kenter shackles). A request gives the total length as a number of shackles.
The grade, stud link or studless, the nominal diameter in mm, the length in shackles of 27.5 m, the class certificate needed, the number of joining shackles (Kenter), the quantity, and a photograph of the marks on an end link of the chain to be replaced.
A reading is a check of the grade and the figures, not an anchoring design. Attach a photograph of the marks on an end link and the certificate number, and Vessel Core checks them before an offer goes back.
