You can access object styles from the Properties palette under Basic. Only the styles defined in your drawing are listed.
Plumbing Line style
Note: If you want to add new styles, modify existing styles, or delete unused styles, use Style Manager. For more information, see Working with Styles.
On the Properties palette, you can also assign a style for the label and flow arrow associated with a piping or plumbing object.
Assigning a piping label style