The National Maritime Union yesterday filed a $40 million damage suit against two ship­ping companies and the rival Seafarers International Union as a dispute over manning four tankers went into its fourth day.  The union also brought charges of unfair labor prac­tices against three companies before the National Labor Re­lations Board here.  Named in the damage action were American Export Is­brandtsen Lines, Isbrandtsen Tankers, Inc. and the Seafarers. Cited in the action before the labor board were American Ex­port, Isbrandtsen Co., Inc. and Isbrandtsen Tankers.  The dispute has idled 11 American Export freighters in United States ports. It stems from an N.M.U. complaint that the four tankers are continuing to be manned by Seafarers crews in violation of the N.M.U. agreement covering the vessels.  The tankers were acquired last year from Colonial Steam­ship Corporation by Western Tankers, Inc., a company con­trolled by Ward Industries, which in turn is controlled by Isbrandtsen Co., Inc. Isbrandt­sen also controls American Ex­port Isbrandtsen Lines. Colonial had a manning contract with the Seafarers for the four tank­ers.  In its suit, the National Mari­time Union charged the com­panies and the S.I.U. with “in­tentional interference with its collective bargaining agree­ment” with the Isbrandtsen companies and “conspiracy to depress labor standards.”  The suit is for damages and for loss of potential earnings by N.M.U. members on the four tankers, for which, according to the N.M.U., Isbrandtsen be­came operating agent last Octo­ber.  From that time on, in the N.M.U.'s view, the company should have complied with its contract by employing N.M.U. crews and meeting N.M.U. la­bor standards.  American Export contends the operation of the tankers does not come under its con­tract with the N.M.U. It has, therefore, sought to bring the dispute before Theodore W. Kheel, impartial arbitrator, on the grounds that the N.M.U. action constituted a violation of the “no strike” clause of its con­tract.  Mr. Kheel held a hearing yes‐ terday, at which he took testi­mony from the company. No union witnesses were heard as the union said it needed niore time to prepare its case. Mr. Kheel said he had set an 11 A.M. deadline today for sub­mission of union testimony.  This article can be viewed in its original form. Please send questions and feedback to archive_feedback@nytimes.com
NMU sues Amer Export, Isbrandtsen Tankers and SIU for $40 million, files unfair labor practice charge with NLRB in dispute over SIU manning of 4 tankers now owned by Western Tankers, indirectly affiliated with Amer Export; 11 Amer Export ships now struck