Bulletin 271 vibration in condensate tanks

September 2023

Manufacturing Engineering

Subject: Vibration in condensate tanks

We have been asked many times why my condensate tank vibrates so much. It could be due to several factors, but first, the condensate tanks are designed to work at atmospheric pressure. When the process is unknown, the condensate returns from the system reach the same operating pressure of the generator, and it is very common for flash steam to form when discharging high temperature condensate, which comes into contact with the low temperature condensate inside the tank. If the thermal jump is not very high, the pockets of steam generated are small, so the steam will condense quickly and we will hear small, cyclical impacts at high speed known as “knocking” . The condensate tank is equipped with two connections for the condensate return, one for low pressure and the other for high pressure. It is a common mistake when all the returns are placed in a single inlet. Remember that it is important that the client or designer Identify the pressure of the returns well, there are four classifications of a condensate system used in plants.

1. Gravity or atmospheric (condensate line pressure maintained at or near zero psi))

2. Low pressure (1 to 15 psi) (0.07 to 1.05 kg/cm²)

3. Medium pressure (16 to 99 psi) (1.13 to 6.96 kg/cm²)

4. High pressure (100 psi or higher) (7 kg/cm² or higher)

Typical installation diagram

Flow 4 lb/h/BHP

SUPPLY STEAM

RETURN COND. HIGH PRESSURE

RETURN COND. LOW PRESSURE

When the returns reach low pressure or atmospheric pressure, an inductor tube is not required, as seen in the diagram. When they reach medium pressure or high pressure, the use of inductor tubes is always recommended.

What is an inductor tube?

The inductor tube is designed with a series of holes along the tube. The condensate return in the tank will mix with the cooler surrounding water in the tank without undue turbulence. High temperature condensate or steam released into a water tank without an inducer tube will cause a fairly violent reaction and considerable noise and vibration. The steam trap and preheat line must be installed in an inducer tube. The inductor must be installed so that the holes are horizontal. If the holes point upward, the discharge from the holes can pass through the water surface of the tank. This action will tend to aerate the water, requiring the use of excessive amounts of oxygen scavenger. Vibration generated as a result of a missing or incorrectly installed inducer tube can cause the tank and associated pipes to move and even rupture pipes if severe enough.

Another detail: installing too many pipes to the same condensate inlet will generate a torque moment greater than calculated, cracking the tank and causing damage to operating personnel.

The Clayton inductor tube is stamped "XX" on the outside of the tubing connection. "XX" should be at the 12 o'clock position facing up when installed.

XX for position of the inducer tube in the tank

assembled inductor tube

Arrangement of 2 inductor tubes in condensate tank

COMMON ERRORS IN INSTALLATIONS

Installation diagram

COMMON ERROR

As we see in this diagram, all returns enter a single inductor tube, this will cause vibration and excessive noise, which will affect the operation of the condensate tank.

COMMON ERROR

As we see in this other diagram, all returns enter a single inductor tube, this will cause vibration and excessive noise, which will affect the operation of the condensate tank. In this case it is very important to highlight, as there will be vibration, the moment or lever arm will be excessive for the connection, it can cause severe damage if the coupling cracks, causing burns to the personnel around.

Installation diagram

It is the responsibility of the installer, contractor and service team to make the corresponding observations indicated in this bulletin.

Guide to selecting inductor tubes.

Part No. UH23844 UH23846 CM23838 CM02327

Description

Used

TH00570 TH01100

18.50” length inductor tub e 25.25” length inductor tub e 30.00” length inductor tub e 48.00” length inductor tub e

TH02100, 2300 y 2500

TH03000