FREQUENTLY ASKED QUESTIONS ABOUT PIPE SUPPORTS.

1. Are pipe supports also applicable for supporting equipment, structures, etc.?
   Yes, they are. In fact, hangers, turnbuckles, eye rods, beam attachments, clamps, etc. are commonly used as their supporting elements.

2. Is PIHASA prepared to manufacture supports other than their standard catalogue items?
   Definitely. Although ordering our catalogue standard items reduces costs and assures immediate shipment, most of our turnover comes from the production of special supports. As a result, we will manufacture any element according to your drawings, or with any variation in dimensions of our standard products, with the same competitive prices and short delivery times.

3. What are spring supports designed for?
   Spring supports' design is based on the use of one or more helicoid springs. They are meant to absorb vertical displacement of pipes which is caused by thermal expansions. The springs are the supporting element of the pipe to the structure.

4. What is the difference between variable and constant spring supports?
   Variable spring supports vary in their load along their travel, while constant supports always carry the same load along their travel.

5. When should we choose variables or constant spring supports?
   There are standard coded rules that limit the load variation of a spring support. This variation is measured in terms of percentage of working load -also known as "hot load"- compared to the installation load -also known as "cold load". This variation for variable spring supports should not exceed 25%, although the engineering can be more restrictive. If no model of variable supports can offer lower variation, constant supports must be chosen instead. Also, as a practical rule, we can make the following recommendations:

TYPE OF SUPPORT	PIHASA MODEL	MAX. TRAVEL
Variable Support	CVC	10/12 mm.
Variable Support	CV	20/25 mm.
Variable Support	CVL	40/50 mm.
Variable Support	CVLL	60/75 mm.
Constant Support	All models	+60/75 mm.

6. What is the temperature criteria to choose alloy steels vs. carbon steels?
   Generally, elements connected to pipes that carry fluids over 350/370ºC (660/700ºF) should be manufactured using alloy steels with Cr and Mo. Also, supporting elements that are welded to a pipe must be of its same quality. Additional factors like corrosion of stainless steel pipes must be taken into account when deciding the quality of materials to be used for pipe supports.

7. What is the maximum working temperature of the most common materials for pipe supports?
   - Carbon Steels-------------------370ºC (700ºF)
   - Alloy Steels Cr-Mo
      1/1'25%Cr and 0'5%Mo------540ºC (1000ºF)
      2/2'5%Cr y and 1%Mo----------595ºC (1100ºF)
   - Austenitic Stainless Steels
      Type 304----------------------600ºC (1100ºF)
      Type 316----------------------650ºC (1200ºF)
   Note: In addition to working temperatures, the maximum acceptable tensions of each material should be taken into account for choosing the most appropriate material.

8. What is the difference between anti-vibrating springs and hydraulic snubbers?
   They are special supporting elements with important differences:
      - Anti-vibrating springs avoid vibrations in the pipes. They are also a support that absorbs the load of the pipe and transmits it to the structure.
      - Snubbers, best called "shock arrestors", do not support loads. Their function is to block themselves and become rigid elements in special circumstances such as earthquakes or strong water hammers.

9. How do we know if a pipe support is working properly?
   Spring supports have two operating marks:
      - Installation position or cold position
      - Operating position or hot position
   These positions are clearly marked in the stainless steel plate that all spring supports carry. During site survey, it is easily checked if the travel indicator is located in the correct position, cold position during plant shutdown, and hot position during normal operation. If the travel indicator differs significantly from its correct position, the support must be inspected and calibrated.

10. When must blocking devices of spring supports be taken out?
   After installing the spring support and its accessories and when the supported pipe will not suffer any modification that can affect working loads. In other words, after finishing the installation of the pipes and equipment as well as the hydraulic pressure tests and cleaning.