Pipe Load
An Introduction To Felt As A Carrier Material For Cured In Place Pipe Lining
An introduction to Selecting Felt Liners.
Felt as a Carrier --The principle of sewer lining using resin impregnated felt requires that felt acts as a sponge, when fully saturated it acts as a carrier material holding a pre-define volume of resin. A felt liner Structure consists of a tube assembled from a pre-determined thickness of felt coated with an impervious outer sleeve Normally PVC or P.U.
The compression characteristics of the felt are critical to the lining process as the design thickness of a liner relates to the cured thickness, when the impregnated liner has been pressurised. For this reason the density and thickness of felt are carefully monitored during production. For larger diameter liners where greater design thickness is required it is usual to build up thickness by adding an addition of one or more internal plain felt tubes. This becomes part of the liner structure during inversion [generally thickness in excess of 6mm will be made up of a double layer and thickness greater than 10mm would be constructed of 3 layers.]
The thickness requirement for a particular job is normally calculated from long term modulus information acquired by type testing of the liner and resin matrix. This information can be used in a calculation that gives the required thickness based on a safe head of water that the liner is required to resist.
Coatings PU or PVC. The most common coatings observed on felt liners are PU or PVC to the general observer the PU [ Poly Urethane] coated liner appears shinny (Gloss) and stiffer to touch, PVC [Poly Vinyl Chloride ] coated liners have a dull (matt) appearance and flexible to touch. The Coating is designed to be impermeable to water at 2 bar and carefully monitored during production to avoid pinholes and porosity. Applying a coating effectively is a very technical process to enable the coating to key itself to the felt.The decision process behind the selection of coating tends to be a function of the installation method. With installation temperature being the major consideration, PU has better resistance to high temperatures during cure and when installed correctly can achieve a better surface finish. PU also has the advantage of being considerably easier to patch. PVC tends to be easier to invert at smaller diameters and resistant to temperature up to approx. 80'C.
Drag in Liners, many small diameter liners [ 4" & 6" particularly ]are installed by the drag-in technique, which involves winching a length of lay-flat liner through the section of drain to be lined and inflated by a separate operation. The inflation is done by inverting a "Calibration Hose" through the centre of the liner, this tube acts as a temporary flexible formwork until the liner is cured. After cure the calibration hose is removed. Liner used for this method of installation has distinct differences from liner installed by other methods. The design of Drag-In liners must take into account the tensile forces of winching to ensure that the material doesn't stretch beyond its designed limits, this could result in thinning of the liner under load. The construction diameter is also different to that of liners installed by other methods as it will not extend radially during insertion.
Inversion Liners – Since the early days of cured in place lining, the water inversion technique has been the most accepted method of installing liners. However , there has always been difficulty in the Inversion of small bore liners without compromising on the quality and finished thickness, this has contributed to the popularity of drag-in liners in the small bore end of the lining market. As a result of more advanced production techniques and installation equipment, inversion liners for small bore pipes are now available to full specification.
The main visible difference between Drag-In and inversion liners is the initial diameter, this is smaller as the liner expands radially during inversion. This is another factor that effects the structure and design of the felt as compression of the felt occurs during installation.
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Pipe Load
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How do you know if an interior wall is a load-bearing wall?
There's a wall between the vanity and a fiberglass tub/shower stall in my master bath. There's no electrical in the wall, or pipes either, as far as I can tell. It's tight up againts the side of the vanity and at the foot of the bathtub, opposite the spigot/shower head. I think it might be there just to support/seperate the shower stall. How can I be sure it's not load-bearing, before I take a hammer to it and it's too late?
If the wall is attached to the trusses (I can get into the attic alright) what will it look like? What will I notice?
Unlikely, but possible. For example, if the roof ridge line runs across the open end of that stub wall it could be that it is load bearing. If the house has a basement or crawl space there would be a post or a beam below this point if it was load bearing. If not it isn't. However, if there is a slab floor it would be difficult to tell if there is a support pad under there since it would be hidden.
If load bearing the stub wall will have at least double studs at the open end, so a finishing nail inserted through the drywall 2.5" (i.e. more than the thickness of drywall plus a stud) back from the front surface of the end of the stub wall may provide a clue. If it hits something it could indicate a post or double stud. If not the wall is not load bearing.
In brief, there should be indicators but without drawings for the house or exploratory work to look it is almost impossible to be certain.
That all said unless the ridge line passes over the end of the stub wall I'd be pretty confident the wall is NOT load bearing.