ASME B29.22-2001 (2016) — Drop Forged Rivetless Chains, Sprocket Teeth, Drive Chain/Drive Dogs

⚙️ ASME B29.22-2001 (reaffirmed 2016), Drop Forged Rivetless Chains, Sprocket Teeth, Drive Chain/Drive Dogs, is the American National Standard defining dimensions and interchangeability requirements for drop forged rivetless chains. The terminology of this chain series was established many years ago and has become generic for this type of chain. A subcommittee was appointed by the ANSI B29 Committee in September 1978 to establish an interchangeability standard for drop forged rivetless chains. These chains are drop forged from heat-treated medium carbon steel and use no rivets — adjacent links engage and articulate through the pin-hole structure of the links themselves, giving a simple, easy-to-assemble, high-capacity chain used in automotive paint and oven lines, bulk conveying, wood processing, foundry, and metallurgical service. This Standard is promulgated for the drop forged type of heat-treated medium carbon steel chain in the sizes that comprise the vast majority of use; cast or fabricated chains of alloys or stainless steel are not considered.

1. Scope and Overview 📌

The Standard specifies dimensions, M.U.T.S., measuring load, strand length tolerance, finish, and chain numbering for drop forged rivetless chains (regular, X-type, and modified X-type), together with sprocket teeth and drive chain/drive dogs. Its purpose is interchangeability: it publishes maximum/minimum controlling dimensions so chains from different manufacturers interconnect, without attempting to establish absolute engineering characteristics or tolerances where interchangeability is not involved. Consistent with all B29 series standards, it does not prescribe manufacturing tolerances beyond what interchangeability requires.

Particularly worthy of note is the relationship between actual and reference pitch. Rivetless chains are, in general, a slight degree longer than reference pitch. This allows the use of ANSI and ISO standard roller chains in combination with attached “dogs” to act as drives. According to the experienced estimate of the subcommittee members, roller chain/dog drives are used with more than half the drop forged rivetless chain systems in existence; such drives permit systems of unlimited length, especially suited to ultra-long conveyor lines.

2. Chain Types and Numbering 🔧

The Standard covers three chain types: Regular, X-Type, and Modified X-Type. The X-type link has an X-shaped cross-section, giving higher stiffness and load capacity for the same material and improving sprocket engagement. Chain numbers use an “X + digits” form (e.g., X348, X458, X678, X100-16), with digits corresponding to the size within the series. The table summarizes typical chain numbers and their drive dogs:

Note: the table is compiled from the chain-to-dog relationships shown in Figs. 9–14 of the Standard; pitch, pin-hole dimensions, chain width, and M.U.T.S. for each chain number are given in Tables 2 through 4 (regular, X-type, modified X-type). Verify against the Standard when specifying.

3. Performance Parameters and Key Definitions 🔩

3.1 Minimum Ultimate Tensile Strength (M.U.T.S.)

M.U.T.S. is the minimum force at which an unused, undamaged chain could fail when subjected to a single tensile loading test. The Standard warns that M.U.T.S. is not a working load — it greatly exceeds the maximum force that may be safely applied, and the tensile test is destructive. Because rivetless chains operate under shock and wear in conveying duty, the actual allowable load must account for dynamic load, wear condition, and safety factors.

3.2 Measuring Load and Strand Length Tolerance

The measuring load is the tension applied when measuring chain length; Table 1 gives maximum and minimum strand tolerances. Because rivetless chains often run in long closed loops, strand length tolerance is especially critical to system synchronization and tensioning; as wear elongates the pitch, compensate with the tensioner and monitor the elongation rate.

4. Sprocket Tooth Form and Drive Dogs 🔧

The Standard specifies Type A and Type B sprocket tooth forms (Figs. 6 and 7), sprocket maximum eccentricity and face runout tolerances (Table 5), and sprocket factors (Table 6) to ensure correct chain-sprocket engagement. Drive dogs are driving elements used with ANSI/ISO standard roller chains, mounted on the rivetless chain and driven by the standard roller chain to drive long conveying systems. The Standard specifies the matching dimensions for the X348/348, X458/458, X678/678, X100-16/100-16, X75-13/75-13, and X150-22/150-22 chain and drive dog combinations (Figs. 9–14).

5. Engineering Practice Essentials 🛠️

• 🔍 Selection workflow: determine conveying load, distance, and speed → select chain type (regular/X-type/modified X-type) and chain number → verify M.U.T.S. against a proper safety factor → choose the drive method (sprocket drive or roller chain + drive dogs) → design sprocket and drive-dog interface to the Standard.
• 🔧 Assembly and finish: apply the finish required by the Standard (e.g., coating/blackening); ensure links engage correctly and drive dogs are securely mounted.
• 📊 Wear and elongation management: periodically measure strand length under the measuring load and monitor pitch elongation; replace sections as a set when wear exceeds limits, avoiding mixing new and worn sections that cause uneven meshing.
• 📋 Interchangeability management: only links, sprockets, and drive dogs made to B29.22-2001 are guaranteed interchangeable; drive dogs from different chain numbers must not be mixed.

6. Frequently Asked Questions ❓