ASME B32.2-1969 (1979) — Preferred Thicknesses for Uncoated Flat Metals (0.020 in. and Over)

📏 ASME B32.2-1969 is the other half of the B32 Committee’s flat-metal sizing system: it defines preferred thicknesses for uncoated flat metal products with nominal thickness 0.020 in. (0.508 mm) and over, complementing B32.1-1952, which covers thicknesses below 0.020 in. Together the two standards span the full thickness range of uncoated flat mill products. Published in 1969 and reaffirmed by ANSI in 1979, it is identified as B32.2-1969 (R1979). The source PDF is a scanned image without an extractable text layer; the content below is reconstructed from the documented history of the B32 program and from metal-sheet industry practice.

The B32 program has a well-documented historical background. In July 1971 the U.S. Department of Commerce submitted to Congress its report “A Metric America — A Decision Whose Time Has Come,” recommending that the United States move to the metric system through a coordinated national program. The subsequent surge of metric activity in industry generated numerous requests from both producers and users that the B32 Committee develop preferred series of metric sizes for the various forms of wrought metal mill products. On January 17, 1973, Subcommittee 1 (flat products) and Subcommittee 2 (round products) were formed; Subcommittee 4 (tubular products) followed on October 24, 1973. The committees were composed of representatives of the major metal trade associations and user groups, and their conclusions drew on three sources of information: preferred-number sizes included in ISO Recommendation R388, sizes actually used in metric countries, and rounded metric equivalents of high-activity inch sizes used in the United States. B32.2, published in 1969 and reaffirmed in 1979, was part of this broader effort to systematize the thickness sizing of flat mill products in a logical, orderly manner.

1. Scope and General Framework 📌

Three keywords define the scope of B32.2-1969:

• Uncoated: base metals without plating, coating, or cladding; coated total thickness falls outside the series.
• Flat metals: rolled products of rectangular cross section (sheet, strip, plate); rounds and tubes are excluded.
• Thickness ≥ 0.020 in.: from 0.020 in. (0.508 mm) upward, typically through about 1 in. (25.4 mm) and beyond for heavy plate.

Its purpose matches B32.1: where general-purpose applications permit latitude, converging size variants improves design interchangeability, reduces inventories, and raises the availability of warehouse stock. The standard explicitly does not preclude off-series sizes for special high-volume requirements, but encourages the preferred series whenever conditions allow.

2. Preferred Thickness Series and Technical Content 📏

The thickness series is built on preferred numbers, mainly the R10 series (ANSI Z17.1 Series 10) advancing about 25 percent per step, with occasional R20 insertions to preserve a uniform geometric progression. The table below shows representative values reconstructed from industry practice for the starting range:

As with B32.1, only nominal preferred thicknesses are specified. Delivery tolerances and the availability of any given thickness in a particular metal and grade are established by the governing material specification and the producer. Useful conversions: 0.020 in. ≈ 0.508 mm, 0.250 in. ≈ 6.35 mm; the metric-era counterpart continues from B32.3M-1984 with its series starting at 0.050 mm. A practical note: the range at and above 0.020 in. spans both what North American practice loosely calls sheet (up to about 3/16 in.) and plate (beyond that). B32.2 makes no such naming distinction — the preferred series advances as one geometric progression — so selection is simply a matter of looking up the nominal thickness in the table.

3. Engineering Practice Points 🛠️

• 🔍 Selection logic: for uncoated flat products 0.020 in. and over, consult the B32.2 series first, then complete material selection based on strength, stiffness, and formability.
• 📦 Plate consolidation: compare common commercial gauges (1/16, 3/32, 1/8, 3/16, 1/4 in.) with the preferred series and consolidate wherever possible to avoid one stock location per thickness.
• 🔧 Tolerance awareness: hot-rolled and cold-rolled sheet of the same nominal thickness have markedly different tolerance bands; specify tolerance and surface condition per the applicable material specification (e.g., the relevant ASTM standard).
• 🔄 Coating allowance: the series addresses uncoated base metal; leave thickness allowance when galvanizing, tinning, or laminating will follow.
• 📋 Order marking: state grade, width, length, thickness, temper, and tolerance; avoid incomplete phrasing such as “per B32.2.”

4. FAQ ❓