Manhole Risers are used when regrading roads and repaving surfaces. Manhole risers and extension rings are a cost effective way to bring existing manhole frame covers and manhole frames and grates to grade. Manhole risers are made in cast iron, mild steel and can be also come furnished in adjustable patterns. We carry various different municipal standards and size specifications. Manhole riser installation is fast, quick and relatively easier opposed to installing a brand new manhole cover.
Manhole Extension Rings are for use on resurfacing projects to raise the elevation of the existing manhole without changing the frame. Extension Rings are easy to install, cost effective and are durable.
Adjustable Risers Specifications
- All material for risers (excluding adjustment device) shall be A.S.T.M. A-36 Steel, meeting 575MQ (HS-20).
- Steel material for lower riser shall be 3/4” minimum thickness.
- Material for upper riser shall be 3/8” minimum thickness.
- On 3 piece riser, material joining upper & lower riser shall be a minimum of 16 gauge A-36 steel, a maximum of 12 gauge, and must be continuous (no “tab joining” allowed) with no exceptions.
- All upper and lower sections of riser bars must be continuously welded with a minimum of 1/8” weld. On 3-piece riser, a 1/8” continuous weld is required along the top, joining the 12 or 16 gauge material. Stitch welded sections are not permitted.
- Adjustment device shall be a minimum 3⁄4” 13 U.N.C. solid 304 Stainless Steel bolt, 4” maximum length. Plated bolts are not acceptable. Adjustment nuts shall be C1020 cold rolled steel, minimum outside diameter shall be 1”, minimum length shall be 1 5/8”, maximum length shall be 1 3⁄4”.
- Adjustment of riser shall be 0” + or – 1⁄2” diameter.
- Risers shall be fabricated to the top of the manhole cover diameter given in a “closed” position.
- All risers shall be coated with black asphalt paint.