The invention relates to covers for wastewater treatment lagoons, which are typically covered by expansive stretches of sheet-form, high density polyethylene (HDPE). The invention more particularly relates to improvements in attaching HDPE patches at distributed locations thereon, which patches provide locally increased thickness to the cover in service as seats for attachment of further attachments to the cover, such as for example and without limitation HDPE straps for retention of HDPE grout-filled ballast pipes, and so on.

A method for welding at least two parts including a thermoplastic material and having respective surfaces to be welded, including: inserting an insert between the surfaces to be welded of the two parts; generating heat via the insert; wherein the insert moves in relation to the parts to be welded in a welding direction. Also, an installation adapted for implementation of this method.

The invention first relates to a method for welding at least two parts comprising a thermoplastic material and having respective surfaces to be welded, comprising: inserting an insert between the surfaces to be welded of the two parts; generating heat via said insert; wherein the insert moves in relation to the parts to be welded in a welding direction. The invention also relates to an installation adapted for implementation of this method.

A process for welding porous membranes, the process containing i) providing first and second porous membranes; ii) at least partially superimposing the first and second porous membranes to obtain an at least partial superimposition region; iii) welding the first and second porous membranes at least in a portion of the at least one superimposition region at a temperature in the range from 100 to 300° C. to obtain an at least partially welded composite of the first and second porous membranes, wherein the first and second porous membranes are made of at least one thermoplastic elastomer selected from the group consisting of a polyurethane elastomer, a polyester elastomer, a polyetherester elastomer, a polyesterester elastomer, a polyamide elastomer, a polyetheramide elastomer, a polystyrene elastomer, and an ethylene-vinyl acetate elastomer, and wherein the first and second porous membranes have pores having an average pore diameter of less than 2000 nm.

Various fabric products incorporating exterior hydrostatic barriers and processes for manufacturing such fabric products are provided.

A process for welding porous membranes, the process containing i) providing first and second porous membranes; ii) at least partially superimposing the first and second porous membranes to obtain an at least partial superimposition region; iii) welding the first and second porous membranes at least in a portion of the at least one superimposition region at a temperature in the range from 100 to 300 C. to obtain an at least partially welded composite of the first and second porous membranes, wherein the first and second porous membranes are made of at least one thermoplastic elastomer selected from the group consisting of a polyurethane elastomer, a polyester elastomer, a polyetherester elastomer, a polyesterester elastomer, a polyamide elastomer, a polyetheramide elastomer, a polystyrene elastomer, and an ethylene-vinyl acetate elastomer, and wherein the first and second porous membranes have pores having an average pore diameter of less than 2000 nm.

A foam pit cover having a cover sheet with a gator clip along its perimeter, a perimeter skirt, an apron, and a plurality of toggle bungee cords. The perimeter skirt is made of primary and second sheets, the primary sheet being longer than the secondary sheet. The toggle bungee cords are configured to fit within grommets in the secondary sheet of the perimeter skirt and the bottom part of the apron. The top part of the apron is attached to the bottom part of the primary sheet of the perimeter skirt. The cover sheet and apron are made of a PVC-coated polyester material, and the perimeter skirt is made of a breathable, durable fabric. The invention optionally includes a top sheet with customized graphics and corner pieces to further secure the cover sheet to the perimeter skirt.

Process for producing a pressure-sensitive adhesive comprising expanded microballoons, wherein the constituents for forming the adhesive are mixed in a first mixing assembly, the mixed adhesive is transferred into a second mixing assembly into which, at the same time, unexpanded microballoons are fed, the microballoons are expanded in the second mixing assembly or on exit from the second mixing assembly, the adhesive mixture with the expanded microballoons is shaped to a layer in a shaping assembly in which expanded microballoons which have broken through the surface are pressed into the layer surface and the layer of adhesive mixture together with the expanded microballoons are optionally applied to a weblike backing material.

A method for forming a geomembrane liner testable for leaks by securing adjacent panels together with the conductivity of the lower surface of an overlying panel broken along a line adjacent the panel overlapping edge, and the overlapping edges sealed along the line. A heat welder has slots for the overlapping panel edges, with a heated wedge between the slots and having a projection to break the conductivity of the overlying panel bottom surface as it passes the wedge. The slots merge to press the liner edges together to heat weld them along the line of broken conductivity as the welder is moved along the panel edges.

A method for forming a geomembrane liner testable for leaks by securing adjacent panels together with the conductivity of the lower surface of an overlying panel broken along a line adjacent the panel overlapping edge, and the overlapping edges sealed along the line. A heat welder has slots for the overlapping panel edges, with a heated wedge between the slots and having a projection to break the conductivity of the overlying panel bottom surface as it passes the wedge. The slots merge to press the liner edges together to heat weld them along the line of broken conductivity as the welder is moved along the panel edges.