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Tech Profiles > Field Modifications

Field Modifications

Many Options And Easier With HOBAS Pipe
No matter how carefully engineered and thoroughly planned, all projects encounter some unknowns and require field changes. This is particularly true when working underground with buried piping. Therefore, in order to improve constructibility and minimize the economic impact of changes, it is desirable and important to use a pipe that can be easily field modified. HOBAS pipes meet this challenge better than any other large diameter product with numerous, cost effective options for length adjustments, closures, special connections, configuration changes, add ons and repairs.

The unique combination of properties and characteristics of HOBAS centrifugal cast fiberglass reinforced polymer mortar pipes allows many economical and frequently quick modification alternatives, even in the field. The key properties and characteristics include a smooth & constant OD surface, dimensional stability, OD’s that match ductile iron pipes from 18″ to 48″, ease of cutting & machining, high stiffness and the capability to bond to surfaces by lamination (“fiberglass welding”).
Length Adjustments
The HOBAS FWC gasket-sealed, push-on coupling seals directly to the unmodified exterior pipe surface. Since the OD is constant along the entire pipe section, field length changes may be accomplished by simply cutting the pipe at the desired location, chamfering the cut end and joining with the FWC coupling. This is true for pressure applications as well as non-pressure service.
Non-pressure field closures may be made using the HOBAS closure coupling after cutting and beveling the pipe end as described above. In some circumstances, Fernco couplings may be suitable. For pressure service closures, use DI mechanical joints (18″ to 48″) or Dresser style couplings to to seal the tie-in pipe. These joints can also be used in non-pressure situations.
Special Connections
Methods to connect to other pipes or structures include wall ring pieces, FWC couplings, DI joints, Dresser style couplings, concrete encasement, flanges, Fernco couplings, lamination, custom fabricated bell or spigot to match, cast-in gaskets and expandable boots.
Configuration Changes
Minor changes to grade or alignment can frequently be achieved by angular rotation of any of the HOBAS gasket-sealed bell-spigot or coupling joints. Greater deviations may require elbows or other fittings. These items are available from the factory or may be field fabricated. The later method is usually chosen when the configuration is determined as the job progresses. Several types of fittings have been successfully field fabricated including elbows, tees and wyes by cutting / mitering pipe sections and structurally connecting them with fiberglass reinforced laminations. Additionally, factory made fittings can be modified in the field to fit changed conditions.
Using the cutting / lamination techniques described previously, outlets or nozzles may be added to an existing pipe or fitting. These items may also be incorporated be other means. In non-pressure systems, laterals are frequently connected using Inserta-Tee fittings or expandable boot accessories. Taps on pressure lines are accomplished using 360 degree tapping sleeves.
There are several options available to repair damaged HOBAS fiberglass pipes:

  1. Damaged ends may be simply cut off and the pipes assembled as previously described in “length adjustments” or “closures”.
  2. For damage away from the ends, a segment containing the affected area may be cut from the pipe and the remaining sections joined as in point (1) above.
  3. Most any type of damage to a HOBAS fiberglass pipe from minor scraps to complete fractures is repairable, even after installation, using fiberglass reinforced laminations. The repair method selection is generally governed by several factors including cost, accessibility, safety, logistics and timing.
Many benefits are derived because of the numerous field modification options available with HOBAS centrifugal cast fiberglass reinforced polymer mortar pipes including:

  1. Faster, cheaper installation
  2. Greater flexibility in solving problems
  3. Lower cost solutions to field changes
  4. Avoid expensive excavations to repair installed buried pipes
  5. Consistent, high performance of field modified pipes and fittings
Save time, money and headaches, specify and use HOBAS centrifugal cast fiberglass reinforced polymer mortar pipes on your next project and enjoy these many, unique benefits.