High Performance Steel Projects
The following bridge owners have projects that did or will require HPS-70W plates. They include departments of transportation (DOT) and highway departments from the states of Tennessee, Nebraska, New York, Massachusetts, North Carolina, Pennsylvania, Virginia, Utah, Colorado, New Jersey, Missouri, Iowa, Illinois, West Virginia, Maine, the New York State Thruway Authority and the Pennsylvania Turnpike Commission.

The Tennessee DOT, using HPS-70W plates for a two-span bridge (236 ft. - 236 ft.) in Jackson County, reported weight savings (vs. Grade 50W) of roughly 25 percent. Final cost savings were about 10 percent. A second HPS bridge was built on Route 52 over the Clear Fork River in June 1997. Due to crane reach limitations, HPS-70W was used to make girder sections as light as possible. This is a 995 ft., four-span structure with a maximum span of 350 ft. Grade HPS-70W was used in the non-composite negative moment field sections and a hybrid section consisting of a 50W compression top flange and web, together with an HPS-70W tension bottom flange in the composite positive moment field sections.

The University of Nebraska at Lincoln is principal investigator for Nebraska's three-phase HPS bridge project. A plate girder bridge built near Snyder, Neb. is now open to traffic. A second-phase bridge is in fabrication, and a third bridge will investigate more innovative uses of the steel.

The New York State Thruway Authority projects involved superstructure replacements for eight bridges, six of which are overpasses. HPS-70W welded plate girders 29 to 30 in. deep were used over two equal spans of approximately 100 ft. Use of this new steel not only permitted removal of two hazardous shoulder piers, but also resulted in an improved under clearance, as the HPS girders replaced 36 in. deep rolled beams.

Fabrication Guidelines
An AISI publication, Guide for Highway Bridge Fabrication with HPS-70W Steel, is available for distribution and was adopted by AASHTO in May 1999. The guide should be used with ANSI/AASHTO/AWS D1.5-95 and is available on the AISI Web site. The guide eventually will be published by AASHTO and removed from the AISI Web site.

Current Welding Guidelines for HPS-70W Minimum preheat and interpass temperature, ºF (ºC) Submerged arc welding with H4 hydrogen control level with pre-qualified consumables Thickness of Thickness Part at Point of Welding of A709    A709 Grade To 3/4 in. (19 mm) Incl. Over 3/4 in. (19 mm) to 1 1/2 in. (38 mm) Incl. Over 1 1/2 in. (38 mm) to 2 1/2 in. (64 mm) Incl. Over 2 1/2 in. (64 mm)  HPS-70W (485W) 50 (10) 70 (21) 70 (21) 125 (52)  70W (485W) 50 (10) 125 (52) 175 (79) 225 (107)    - Maximum interpass temperature 450ºF (232ºC)    - Heat input 40 - 90 KJ/in. (1.6 - 3.5 KJ/mm)

The suggested welding practices should be taken from this guide. The improved weldability of this grade is demonstrated by the above comparison to the original grade 70W.