Manhole Inserts and Manhole Insert Gasket Fabrication Methods

Abstract

Methods of fabricating a manhole insert gasket on a manhole insert flange of a manhole insert include fabricating a gasket mold, inverting a manhole insert having a manhole insert flange, placing the manhole insert on the gasket mold with a mold space overlying the manhole insert flange, preparing a gasket material, placing the gasket material in the mold space, finishing the manhole insert gasket by curing the gasket material and removing the manhole insert from the gasket mold. Manhole inserts having a manhole insert gasket characterized by enhanced sealing capability and longevity are also disclosed.

What is claimed is: 
     
         1 . A manhole insert, comprising:
 a manhole insert bottom;   a manhole insert sidewall extending from the manhole insert bottom;   a manhole insert flange extending from the manhole insert sidewall; and   a manhole insert gasket on the manhole insert flange, the manhole insert gasket including:
 a gasket material having a two-part polyurethane elastomer prepared by mixing a first part having poly[oxy(methyl-1,2-thanediyl)], alpha-hydro-omega-hydroxy-polymer with 1,3-diisocyanato-2-methylbenzene and 2,4-diisicyanato-1-methylbenzene; dipropylene glycol dibenzoate; and toluene 2,4-diisocyanate with a second part having polypropylene glycol, diethyltoluenediamine and neodecanoic acid, bismuth (3+) salt. 
   
     
     
         2 . The manhole insert of  claim 1  wherein the poly[oxy(methyl-1,2-thanediyl)], alpha-hydro-omega-hydroxy-polymer with 1,3-diisocyanato-2-methylbenzene and 2,4-diisicyanato-1-methylbenzene is present in the first part of the gasket material in a quantity of about 60-80% by weight; the dipropylene glycol dibenzoate is present in the first part of the gasket material in a quantity of about 10-15% by weight; and the toluene 2,4-diisocyanate is present in the first part of the gasket material in a quantity of less than about 1% by weight. 
     
     
         3 . The manhole insert of  claim 1  wherein the polypropylene glycol is present in the second part of the gasket material in a quantity of about 85-95% by weight; the diethyltoluenediamine is present in the second part of the gasket material in a quantity of about 5-15% by weight; and the neodecanoic acid, bismuth (3+) salt is present in the second part of the gasket material in a quantity of less than about 1% by weight. 
     
     
         4 . The manhole insert of  claim 1  wherein the manhole insert gasket is prepared by:
 fabricating a gasket mold; 
 inverting the manhole insert; 
 placing the manhole insert on the gasket mold with a mold space overlying the manhole insert flange; 
 preparing the gasket material; 
 placing the gasket material in the mold space; 
 finishing the manhole insert gasket by curing the gasket material; and 
 removing the manhole insert from the gasket mold. 
 
     
     
         5 . The manhole insert of  claim 4  wherein fabricating a gasket mold comprises preparing a mold board having an outer mold board surface and an inner mold board surface, extending at least one mold board support member from the outer mold board surface, extending at least one manhole insert support member from the inner mold board surface and securing a mold wall against the manhole insert flange of the manhole insert with the mold space overlying the manhole insert flange between the manhole insert and the mold wall, and further comprising placing the at least one mold board support member on a flat, level support surface, and wherein placing the manhole insert on the gasket mold comprises placing the manhole insert on the at least one manhole insert support member. 
     
     
         6 . The manhole insert of  claim 1  further comprising a plurality of insert stiffeners provided in the manhole insert bottom. 
     
     
         7 . The manhole insert of  claim 1  further comprising a manhole insert interior formed by and between the manhole insert bottom and the manhole insert sidewall. 
     
     
         8 . The manhole insert of  claim 1  wherein the manhole insert flange has a manhole insert flange bottom surface, and the manhole insert gasket is provided on the manhole insert flange bottom surface of the manhole insert flange. 
     
     
         9 . A manhole insert, comprising:
 a manhole insert bottom;   a manhole insert sidewall extending from the manhole insert bottom;   a manhole insert flange extending from the manhole insert sidewall; and   a manhole insert gasket on the manhole insert flange, the manhole insert gasket including:
 a gasket material having a two-part polyurethane elastomer prepared by mixing a first part having poly[oxy(methyl-1,2-thanediyl)], alpha-hydro-omega-hydroxy-polymer with 1,3-diisocyanato-2-methylbenzene and 2,4-diisicyanato-1-methylbenzene; dipropylene glycol dibenzoate; and toluene 2,4-diisocyanate with a second part having polypropylene glycol, diethyltoluenediamine and neodecanoic acid, bismuth (3+) salt; 
 wherein the poly[oxy(methyl-1,2-thanediyl)], alpha-hydro-omega-hydroxy-polymer with 1,3-diisocyanato-2-methylbenzene and 2,4-diisicyanato-1-methylbenzene is present in the first part of the gasket material in a quantity of about 60-80% by weight; the dipropylene glycol dibenzoate is present in the first part of the gasket material in a quantity of about 10-15% by weight; and the toluene 2,4-diisocyanate is present in the first part of the gasket material in a quantity of less than about 1% by weight; and 
 wherein the polypropylene glycol is present in the second part of the gasket material in a quantity of about 85-95% by weight; the diethyltoluenediamine is present in the second part of the gasket material in a quantity of about 5-15% by weight; and the neodecanoic acid, bismuth (3+) salt is present in the second part of the gasket material in a quantity of less than about 1% by weight. 
   
     
     
         10 . The manhole insert of  claim 9  wherein the manhole insert gasket is prepared by:
 fabricating a gasket mold; 
 inverting the manhole insert; 
 placing the manhole insert on the gasket mold with a mold space overlying the manhole insert flange; 
 preparing the gasket material; 
 placing the gasket material in the mold space; 
 finishing the manhole insert gasket by curing the gasket material; and 
 removing the manhole insert from the gasket mold. 
 
     
     
         11 . The manhole insert of  claim 10  wherein fabricating a gasket mold comprises preparing a mold board having an outer mold board surface and an inner mold board surface, extending at least one mold board support member from the outer mold board surface, extending at least one manhole insert support member from the inner mold board surface and securing a mold wall against the manhole insert flange of the manhole insert with the mold space overlying the manhole insert flange between the manhole insert and the mold wall, and further comprising placing the at least one mold board support member on a flat, level support surface, and wherein placing the manhole insert on the gasket mold comprises placing the manhole insert on the at least one manhole insert support member. 
     
     
         12 . The manhole insert of  claim 9  further comprising a plurality of insert stiffeners provided in the manhole insert bottom. 
     
     
         13 . The manhole insert of  claim 9  further comprising a manhole insert interior formed by and between the manhole insert bottom and the manhole insert sidewall. 
     
     
         14 . The manhole insert of  claim 9  wherein the manhole insert flange has a manhole insert flange bottom surface, and the manhole insert gasket is provided on the manhole insert flange bottom surface of the manhole insert flange. 
     
     
         15 . A manhole structure, comprising:
 a manhole structure frame configured to enclose a manhole opening and overlie a subterranean sanitary sewer system, the manhole structure frame having a manhole shoulder;
 a manhole insert including:
 a manhole insert bottom; 
 a manhole insert sidewall extending from the manhole insert bottom; 
 a manhole insert flange extending from the manhole insert sidewall; and 
 a manhole insert gasket on the manhole insert flange, the manhole insert gasket having:
 a gasket material including a two-part polyurethane elastomer prepared by mixing a first part having poly[oxy(methyl-1,2-thanediyl)], alpha-hydro-omega-hydroxy-polymer with 1,3-diisocyanato-2-methylbenzene and 2,4-diisicyanato-1-methylbenzene; dipropylene glycol dibenzoate; and toluene 2,4-diisocyanate with a second part having polypropylene glycol, diethyltoluenediamine and neodecanoic acid, bismuth (3+) salt; and 
 
 
 the manhole insert is placed in the manhole opening with the manhole insert gasket seated on the manhole shoulder in the manhole structure frame of the manhole structure. 
   
     
     
         16 . The manhole structure of  claim 15  wherein the poly[oxy(methyl-1,2-thanediyl)], alpha-hydro-omega-hydroxy-polymer with 1,3-diisocyanato-2-methylbenzene and 2,4-diisicyanato-1-methylbenzene is present in the first part of the gasket material in a quantity of about 60-80% by weight; the dipropylene glycol dibenzoate is present in the first part of the gasket material in a quantity of about 10-15% by weight; and the toluene 2,4-diisocyanate is present in the first part of the gasket material in a quantity of less than about 1% by weight. 
     
     
         17 . The manhole structure of  claim 15  wherein the polypropylene glycol is present in the second part of the gasket material in a quantity of about 85-95% by weight; the diethyltoluenediamine is present in the second part of the gasket material in a quantity of about 5-15% by weight; and the neodecanoic acid, bismuth (3+) salt is present in the second part of the gasket material in a quantity of less than about 1% by weight. 
     
     
         18 . The manhole structure of  claim 15  wherein the manhole insert gasket is prepared by:
 fabricating a gasket mold; 
 inverting the manhole insert; 
 placing the manhole insert on the gasket mold with a mold space overlying the manhole insert flange; 
 preparing the gasket material; 
 placing the gasket material in the mold space; 
 finishing the manhole insert gasket by curing the gasket material; and 
 removing the manhole insert from the gasket mold. 
 
     
     
         19 . The manhole structure of  claim 18  wherein fabricating a gasket mold comprises preparing a mold board having an outer mold board surface and an inner mold board surface, extending at least one mold board support member from the outer mold board surface, extending at least one manhole insert support member from the inner mold board surface and securing a mold wall against the manhole insert flange of the manhole insert with the mold space overlying the manhole insert flange between the manhole insert and the mold wall, and further comprising placing the at least one mold board support member on a flat, level support surface, and wherein placing the manhole insert on the gasket mold comprises placing the manhole insert on the at least one manhole insert support member. 
     
     
         20 . The manhole structure of  claim 15  wherein the manhole insert flange has a manhole insert flange bottom surface, and the manhole insert gasket is provided on the manhole insert flange bottom surface of the manhole insert flange.