NOS4-1, Inc., formerly Williams Industrial Services Group Inc, provides infrastructure services, including construction, maintenance and support, to customers in energy, power and industrial end markets. It provides these services both on a constant presence basis and for discrete projects. Its services include plant maintenance, modification and construction; water/wastewater system new installation, expansions and modifications; painting and coatings; insulation; asbestos and lead abatement; roofing systems; and analog to digital conversions. It provides a range of critical services, including maintenance, modification, repair and other capital project services. It installs, maintains and modifies water and wastewater systems, including piping, pumping, storage tank and other related facilities. It offers cleaning, surface preparation, coatings application, quality control and inspection testing on coating projects for nuclear and fossil fuel power plants and others.
WILLIAMS INDUSTRIAL SERVICES GROUP INC. 
