Figure 2-17. - Removing expand able plug from economizer element.

plug from turning, as you tighten the nut. As you tighten the nut using an open-end wrench or a socket wrench, the gaskets expand radially, as they are compressed axially.

The removal of an expandable plug is shown in figure 2-17. Insert a socket wrench or an open-end wrench through the handhole and remove the retainer nut. Insert the economizer plug extractor and then thread it onto the retainer. Place the handhole plate binder in position over the extractor and the thread on the handhole fitting nut. As you tighten the nut, the plug pulls out.

Q5. What five items of information are generally required on boiler tubes?

Q6. When tubes on a boiler drum or header made of 4-6 choromium steel are removed what method of removal cannot be used?

Q7. When tubes are fitted, tubes up to 2-inch-outside diameter should project how far into the drum or header?

Q8. Tubes 2 inches or larger should be belled between what size range?

Q9. What should you do to a plugged boiler tube to avoid pressure buildup in the tube when the boiler is operating?

REPAIRING BOILER REFRACTORIES

Learning Objective: Recognize maintenance and repair procedures for boiler refractories.

Furnaces are built with high-grade, fire-resistant materials that take a lot of punishment. Sooner or later, however, repairs become necessary. Furnace walls or floor may need repairing. The procedure for this repair is as follows:

First, mix the mortar, using a Navy-recommended fire clay or fire cement and fresh water. Do not add anything else. Make the mortar rather thin and without lumps.

Inspect the bricks for flaws and evenness. Choose the best edge for the furnace side. Dip the brick in fresh water and allow the excess water to drip off.

Now, dip one end and side of the brick into the mortar, using an edgewise motion to prevent air bubbles from forming. Lift the brick from the mortar and allow the excess mortar to drip off. Do not place any mortar on the wall or brick with a trowel.-The mortar sticking to the brick is all that is used.

If the mortar is too thick, you will not get the thin joints that you want. The mortar should be a little thinner than the usual wall plaster. You can feel the proper thickness with your hand. Some mortar will stick to your hand, as you lift it away from the mortar. Add more clay or water as necessary, and stir the batch often to keep the mortar at the desired consistency.

Place the brick quickly in position in the wall and pound it in place with a wooden mallet until no mortar can be forced out of the joints. With high-grade brick, joints can be made less than one thirty-second of an inch thick. Joints should never exceed one-sixteenth of an inch.

With a small trowel, fill in any unevenness in the furnace side of the seam and bead over the joints, as shown in figure 2-18. Be sure that no edges of the brick are exposed. The wall should be laid up evenly and smoothly. Any excess mortar that protrudes from the joints should be smoothed off with a small trowel, so the corners of the brick are protected.

Allow the wall to dry for about 12 hours with the burner shutters open to allow circulation of air, which permits the escape of some of the water added to the mortar. As soon thereafter as practicable, light the burner under the boiler and slowly bring the furnace up to operating temperature to bond the mortar to the adjacent brickwork.

Figure 2-18. - Cementing brick.