This IM covers the approval process to supply high strength fasteners to Iowa DOT projects and the inspection, sampling and testing, of high strength and non-high strength fasteners for of all specified applications. The requirements for high strength and non-high strength fasteners can be found in standard specification 4153.06.  High Strength fasteners shall also comply with the Buy America requirements of IM 107.  Manufacturers of high strength fasteners can be found in the Materials Approved Products Listing Enterprise (MAPLE).



Prior to furnishing high strength fasteners on a certification basis, the following documents shall be submitted:


1.     A request shall be submitted to Central Construction and Materials Office in Ames, Iowa detailing the location of the manufacturing plant and any distribution center(s).


2.     Quality control plan/procedures the company has established to ensure material quality and identity through the manufacturing process as well as quality control testing.


3.     A typical example of certification documents the mill will furnish.


4.     Copy of an identification list, invoice or bill of materials providing the information identified in the Certification Procedures.


Upon satisfactory review of this application, the manufacturing mill will be placed on the approved list in Appendix D.  There is no approved list for non-high strength fasteners.




·        The manufacturer of high strength bolts, nuts and washers shall furnish an identification list, invoice or bill of loading for each shipment to each project.  It shall show the project, design number, heat number, hardness, tensile and yield strengths, proof load, zinc coating methods and measured coating thickness, rotational capacity test results, source and number and weight of pieces in the shipment and contain a certification statement indicating the attached mill test reports and galvanization certifications represent the itemized material.

In addition, the name and location of the galvanization plant and supplier if different from the galvanization plant must be shown.

·        The signed mill test reports/certification shall include the chemical and heat analyses, and type for each heat. 

·        The signed mill test reports/certification shall also include a statement indicating the steel meets the requirements of IM 107, Group 1, Buy America.

·        The manufacturer of non-high strength bolts, nuts and washers shall furnish a certification with a statement indicating the nuts, bolts and washers meet the applicable specifications.


A copy of these documents is required for each shipment to a project and shall be provided to the Project Engineer and the District Materials Office responsible for project administration or warehouse stock monitoring.



Acceptance of high strength and non-high strength fasteners will be based on complying verification test samples and certification documentation as indicated above.


Approved sources of high strength fasteners are found in IM 453.06B Appendix D.



High Strength Fasteners (Bolt, Nut & Washer)


                                       Bolts                                                      Nuts & Washers


                                                      Min. No.                                                                 Min. No.

            No. of Pieces in                 Sampled                      No. of Pieces                     Sampled

            a Production Lot                & Tested                      in a PO Lot                        & Tested


            800 and under                        1                            800 and under                          1

            801 to 8,000                            2                            801 to 8,000                             2

            8,001 to 35,000                       3                            8,001 to 22,000                        3

            35,001 to 150,000                   8                            Over 22,000                             5

            150,001 and Over                 13


A copy of the Manufacturer-Certified Test Report, Mill Test Report, and rotational capacity test must be forwarded with the sample as appropriate.


Rotational capacity testing will be in accordance with IM 391 for Long Bolts in Tension Calibrator and IM 392 for Bolts Too Short to Fit in Tension Calibrator. 


Fasteners which fail to meet the requirements of any specified ASTM Specification shall be rejected or, at contractor option, will be re-sampled and tested at two times the original rate. All additional samples shall conform to the specifications or the production lot will be rejected.


If a production lot represents less than 20 fastener assemblies (bolts, nuts, or washers), the District Materials Engineer may, without sampling, accept the small quantity lot on a basis of Manufacturer-Certified Test Report Certification.