9-59 Section 908. Miscellaneous Metal Products
908.01 General Requirements
Miscellaneous metal products must meet the requirements of this section and the contract.
908.02 Testing
Miscellaneous metals product testing will be in accordance with the specified ASTM, AASHTO , or Department methods, as modified by this section.
908.03 Malleable Iron Castings
Malleable iron c astings must meet the requirements of ASTM A47/A47M for Grade 22010.
908.04 Steel Castings
Steel castings for steel construction must meet the requirements of ASTM A148/A148M for Grade 90- 60 carbon steel castings, as shown on the plan s, unless otherwise approved by the Engineer . Steel castings must be heat treated by full annealing, unless otherwise required. Blow holes on finished castings must be located so that a straight line laid in any direction will not cut a total length of cavity greater than 1 inch in any 12 inches . Single blow holes must not exceed 0.500 square inch or have a depth that will affect the strength of the casting.
908.05 Iron Castings
Gray iron castings mus t meet the requirements of AASHTO M306, Class 35B , for manholes, catch basins, leaching basins, inlets, iron steps, and bridge deck drains . Ductile iron castings meeting the requirements of AASHTO M306, Grade 70-50- 05 or Grade 80- 55-06, are an acceptable alternative to gray iron when shown on the plans . Castings must be certified to proof load testing of 50,000 pounds . Coat exposed casting surfaces with asphaltic paint . The coating must be smooth, tough, and tenacious when cold and must not scale -off, tack, or become brittle.
908.06 Bronze or Copper -Alloys for Structures
Washers, bearing, and expansion plates for bridges must meet the requirements of ASTM B22 /B22M for Copper Alloy UNS No. C91100 bronze castings or the requirements of ASTM B100 for Copper Alloy UNS No. C51000 copper alloy plates and sheets . Provide bronze castings that are free of deleterious material, casting faults, injurious blow holes, and other defects. MDOT Standard Specifications for Construction Section 908 9-60 Finished parts must be within 5% of the r equired thickness and within 0.125 inch of the required width and length shown on the plans . Mating curved surfaces must have a curvature radius no greater than +0.010 inch on concave surfaces and no less than −0.010 inch on convex surfaces shown on the plans . Flat machined surfaces must meet the required dimensions within 0.0005 inch per 1.0 inch. The surface roughness of bronze or steel must not be greater than 125 micro inches per inch root mean square.
908.07 Sheet Lead
Sheet lead must meet the requirements of ASTM B29 for desilverized pig lead.
908.08 Sheet Copper
Sheet copper must meet the requirements of ASTM B370.
908.09 Tubing, Steel Railings
A.Base Plates, Angle s, and Post Elements. Base plate, angle, rail splice, and non-tubular post elements must meet the material requirements of ASTM A36 /A36M and galvanizing requirements of ASTM A123/A 123M . Tubular post elements must meet the material requirements of ASTM A500/A500M , Grade B , and galvanizing requirements of ASTM A123/A123M . Silicon content must be less than 0.06 % or from 0.15 to 0.25% . Base plate and post elements must meet the Charpy V -notch impact requirements specified in subsection 906.04.A at a test temperature of 10°F.
B.Rail Elements . Rail elements must meet the material requirements of ASTM A500 /A500M , Grade B , and galvanizing requirements of ASTM A123/A123M . Silicon content must be less than 0.06 % or from 0.15 to 0.25% . Provide the Engineer with one copy of the Mill Test Report (MTR) verifying chemical and physical requirements for structural steel rail element s. Provide an affidavit stating that the material meets specifications . If the MTR is unavailable, arrange for tests of chemical and physical properties and provide certified copies of the test reports and affidavits to the Engineer at no additional cost t o the Department . The Contractor has the option of re-testing a rail sample if it failed elongation and passed all other chemical and physical requirements. The Contractor must drop-weight tear test rail elements from all heats supplied in accordance with ASTM E436 except as modified herein. Drop-weight tear testing is not required on hollow structural section ( HSS) MDOT Standard Specifications for Construction Section 908 9-61 2 by 2 rail elements . Do not heat treat failed heats and do not provide failed heats to the fabricator . The Contractor must conduct the drop-we ight tear test on each heat at 0°F on 2- by 9-inch specimens, supported to achieve a 7-inch span. The Contractor must test three specimens from each of three sides that do not contain a weld to determine the percent shear area. The Contractor must disregard the shear areas of the three specimens from the side with the lowest average shear area and base the final average on the remaining six specimens . Material with an average percent shear area below 50 % is not allowed ; however, if the average percent shear area is between 30 and 50% , the Department will allow the Contractor to retest the material . The r etest sampling frequency is three times that of the first test, and all sample test results must be included in calculating the average. Retested material must have a minimum average percent shear area of 50 %. The manufacturer of the tubular railing must identify the product as follows:
1.Place identification before galvanizing;
2.Include heat number or other code traceable to the heat number;
3.Include manufacturer ’s unique identification code;
4.Place identification on only one section face;
5.Repeat identification at no more than 4-foot intervals;
6.Do not extend identification into the curved surfaces at corners of section; and
7.Do not place identification on side facing traffic or side opposite traffic.
C.Hardware. Railing anchor studs must meet the requirements of ASTM A449, Type 1. Structural bolts must meet the requirements of ASTM F3125/F3125M, Grade A325, Type 1. Round head structural bolts must meet the requirements of ASTM A449, Type 1. The material for the railing hand hole screws must meet the requirements of ASTM A276/A276M , Type 304. Nuts must meet the requirements of ASTM A563, Grade DH , or AASHTO M292 , Grade 2H . Flat, circular washers must meet the requirements of ASTM F436/F436M . Lock washers must be steel, regular, helical spring washers meeting the requirements of A SME B18.21.1. Bolts, anchor studs, nuts, and washers must be hot -dip galvanized in accordance with AASH TO M232 . Galvanized nuts must be tapped oversize in accordance with ASTM A563 and meet supplementary requirements S1 and S2. MDOT Standard Specifications for Construction Section 908 9-62 908.10. Hardware for Timber Construction Machine bolts, drift bolts, and dowels for timber construction must be made of structural grade st eel. Washers must be cast iron ogee or malleable castings . Nails must be cut or round wire of standard form . Spikes must be cut or wire spikes or boat spikes . Galvanize in accordance with AASHTO M232 when required.
908.11 Steel Beam Guardrail Elements, Hardware, and Steel Sleeves
A.Steel Beam Elements and End Sections. Unless otherwise specified on the plans and details, provide steel beam elements and terminal end shoes meeting the requirements of AASHTO M180 for Clas s A guardrail . Thrie beam elements for bridge rail retrofit, special end shoes, and thrie beam terminal connectors must meet the requirements of AASHTO M180 for Class B guardrail. Provide steel beam elements and end sections in the required shape. Steel be am elements and end sections must be hot -dip zinc coated after fabrication in accordance with AASHTO M180 for Type II zinc coatings . W-beam elements may be hot -dip zinc coated before or after fabrication.
B.Hardware. Bolts, nuts, washers, and other guardrail hardware must be hot-dip galvanized in accordance with AASHTO M232 . Bolts must meet the requirements of ASTM A307, Grade A . Nuts must meet the requirements of ASTM A563, Grade A with supplementary requirement S1. Flat circular washers must meet the requirements of ASTM F436/F436M. Beveled square or rectangular washers must meet the requirements of ASTM F436/F436M and the dimensions shown on the plans. Bolts and nuts for m aking splices and connections of beam elements, other than at bridge barrier railings, must meet the requirements of AASHTO M180 . Provide bolts meeting one of the bolt head configurations of AASHTO M180 (Alternate No. 1 or 2) except within the limits of guardrail approach terminals. Hardware for guardrail approach terminals must conform to manufacturer ’s specifications. Structural b olts for connections at bridge railings must conform to ASTM F3125/F3125M, Grade A325, Type 1. N uts must meet the requirements of ASTM A563 , Grade DH , or ASTM A194/A194M, Grade 2H . Flat circular washers must meet the requirements of ASTM F436/F436M . Wire rope and fittings for the cable anchorage must conform to AASHTO M30. Wire rope must be Type II with a Class B coating. MDOT Standard Specifications for Construction Section 908 9-63 C. Stee l Sleeves, Soil Plates, and Bearing Plates. Provide steel sleeves with the inside dimensions shown on the plans within a tolerance, after galvanizing, of +⅛ inch. Provide steel plates in the sizes shown o n the plans but no more than 0.250 inch larger. Steel for the sleeves and plates for wood guardrail posts must meet the requirements of ASTM A36 /A36M or ASTM A1011 /A1011M for Grade 36 or Grade 40. Steel sleeves must have one or two complete penetration longitudinal welds that run along the length of the sleeve. Hot-dip galvanize sleeves and plates in accordance with A ASHTO M111 . The weight of the zinc coating on the sleeves must average at least 2.0 ounces per square foot and each sleeve must have at least 1.7 ounces of zinc coating per square foot . The weight of the zinc coating on plates must average at least 2.3 ounces per square foot , and each plate must have at least 2.0 ounces of zinc coating per square foot.
908.12 Steel Posts for Guardrail
Steel posts for guardrail must be W6 by 9 or W6 by 8.5 section steel posts of the length shown on the plans for guardrail . Each steel post must weigh at least 9.0 pounds per foot . Posts must be fabricated from ASTM A36 /A36M structural steel. Hot-dip galvanize posts in accordance with AASHTO M111 to produce an average coating weight of at least 2.0 ounces per square foot of surface area.
908.13 Guardrail Ref lectors
Fabricate guardrail reflectors from at least 13-gauge steel sheets, galvanized in accordance with ASTM A653/A653M , coating designation G210, and as required. Use Type XI reflective sheeting meeting the requirements of subsection 919.03.B. Prepare galvanized surfaces in accordance with the sheeting manufacturer ’s recommendations before applying the sheeting. Bond reflective material to the galvanized steel.
908.14 Anchor Bolts, Nuts, and Washers
A.General . The fabricator or supplier must provide a Mill Test Report (MTR) that shows compliance with ASTM F1554 for the grade specified in the contract in addition to the following:
1.Heat number;
2.Yield strength; MDOT Standard Specifications for Construction Section 908 9-64 3. Tensile strength;
4.Elongation;
5.Reduction of ar ea; and
6.Charpy V -notch. Provide the furnace lot number for all heat -treated anchor bolts . Order additional bolts to replace those used for Department testing . Each anchor bolt must be provided with two washers and two nuts unless otherwise required in the contract. Provide bolts, nuts, and washers in the size and shape shown on the plans and hot-dip galvanized in accordance with A ASHTO M232. Galvanize the exposed threaded end of anchor bolts a minimum of 20 inches. Nuts must meet the requirements of ASTM A563, Grade DH , or ASTM A194/A194M , Grade 2H . Lubricate nuts in accordance with ASTM A563, supplementary requirement S1 and S2. Re-tap nuts after galvanizing in accordance with ASTM A563 . Provide flat , circular washers meeting the requirements of ASTM F436/F436M.
B.Anchor Bolts and Nuts for Cantilever and Truss Sign Supports, Light Standards, Dynamic Message Sign, CCTV Poles, Tower Lighting Units, and Traffic Signals Mast Signal Arm Poles. Steel anchor bolts must meet the requirements of subsection 908.14.A except that anchor bolt material must meet ASTM F1554, Grade 55, supplemental requirements S1, S3, and S4. Table 908- 1: Anchor Bolt Specifications Characteristic Specification Yield strength 55 ksi Ultimate strength 75–95 ksi Elongation (2 -inch gauge) ≥21%(a) Reduction in area ≥30%(b) Longitudinal Charpy V -notch ≥15 ft -lb at 40°F
a.Elongation (8-in ch gauge), min imum 18% for bolts tested full section
b.Bolts >2 to 2.5 in ches , 22% minimum; >2.5 to 3 inches , 20% minimum The Department will perform Charpy V -notch toughness tests on specimens in accordance with f requency (P) testing of AASHTO T243 orienting the notch perpendicular to the longitudinal axis of the anchor MDOT Standard Specifications for Construction Section 908 9-65 bolt. If necessary, heat treat steel to meet Charpy V -notch toughness requirements. Bolt threads must meet the requirements of ASME B1.1, 8UN series, Class 2A tolerances , before coating. After coating, the maximum limit of pitch and major diameter for bolts with a diameter no greater than 1 inch may exceed the Class 2A limit by no more than 0.021 inch and by no greater than 0.031 inch for bolts greater than 1 inch in diameter. Nut threads must meet the requirements of A SME B1.1, 8UN series , Class 2B tolerances . Tap nuts for anchor bolts less than 1 inch in diameter no greater than 0.021 inch and nuts for anchor bolts equal to or greater than 1 inch in diameter no greater than 0.031 inch.
C.Anchor Bolts for Traffic Signal Strain Poles . Provide anchor bolts that meet subsection 908.14. A with the following exceptions and additions:
1.ASTM F1554, Grade 105, supplementary requirement S3;
2.Coarse pitch threads are acceptable if the anc hor bolts meet required tolerances ;
3.Bolts must be threaded at least 9 inches at the upper end; and
4.Each anchor bolt must be provided with one steel lock washer meeting the requirements of ASME B18.21.1.
D.Anchor Bolts for Other Purposes . Steel anchor bolts must meet subsection 908.14.A except that anchor bolt material must meet ASTM F1554, Grade 36, supplementary requirements .
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 869–875 of 1,146.